A

Symbol for Amperes, which is the basic unit of , defined as one Coulomb of charge per second; see also

A1A

See

A3E

See

absorption

• Intake or assimilation (acceptance, unlike either or passing through) of by the or other object
• Rate or amount of collected by the human body as a result of

AC

alternating current : electric charge flow () that periodically reverses direction at a regular pace, known as its ; see also

AC coupling

See

ACDS

automatically controlled digital station : unattended that communicates primarily in , similar to a , and typically on ; see also

AC line noise / AC line interference

See

AC power

See

AC power line / AC line

See

across the pond

Slang for the other side of the ocean or across the ocean (typically the Atlantic, and often between the US and the UK, but not necessarily)
We might need to start sending across the pond again

ACSSB

amplitude-companded single-sideband : narrowband technique that uses to compresses an signal and it with a pilot signal prior to transmission, then expand (decompress) the signal during reception, using the pilot signal as a reference, which improves the effective audio range of the signal; see also

activation

Act of alerting, intiating, mobilizing, and setting in motion a trained (such as and ) to provide and apply their efforts in a timely manner

active component

Discrete part that requires or supplies a source of electrical energy to perform its function, such as a , , , , or display; see also

active element

See

active power

See

active repeater

• One that is currently operational
• See (opposed to )

adaptive filter

used in to remove unwanted from a received signal; see also

ADC

ADIF

amateur data interchange format : standard for the format of exported files; see also the main

admittance

Quantity of allowance for flow in a circuit, expressed in siemens (symbol S) and defined as the reciprocal of , such that Y = G + jB, in which Y is the admittance, G is the real , j is the imaginary unit, and B is the see also

aerial

AF

AFC

automatic frequency control also automatic fine-tuning control : circuit that keeps the on the selected , preventing it from from drifting; see also

AFCI

affirmative / affirm

yes; see also

AFSK

audio frequency-shift keying : type of in which digital is represented by changes in the frequency (pitch) of an tone (typically from a sound card) to shift the of the transmitted (typically ) signal; see also and

again

repeat it : request to repeat a or other identifying information, such as a section or contest serial number
Again? (please repeat that)
Again, again? (please repeat that at least two more times)

AGC

AGL

above ground level : height measured with respect to the underlying ground surface; see also

AGM absorbed glass mat : type of whose acid electrolyte is held in fiberglass mesh mats that surround conductive lead plates, and often used in radio as electrical storage; see also

AGN

(please repeat what you just sent); see also

A-index / A index / A_P-index

See

AIP

advanced intercept point : feature introduced by , in which the can be manually adjusted, to help extend its while reducing both nearby signal and

air

• Slang for reference to a transmission or in general, as in or or or or
• Slang for presention of a net or (typically ) program on
  When will the net air?

air-core transformer whose wires or other conductors are wound around an air-filled core, such as a non-magnetic tube or form, used for very applications; see also

air-core transformer

air-core transformer symbol

air time / airtime

• Slang for duration of a particular transmission
  How long was my air time when I gave my ?
• Slang for duration of a or other (typically ) program that is held over
• Slang for schedule (date, time, , etc.) for a transmission or (typically ) program to be held on ; see also
  Let me know when the net's air time is

air waves

Slang for organized or in general; see also and and
You should announce that over the air waves

A_L / AL

See

ALC

ALE

alien

• Person residing in the US, but is not a US citizen (also called resident alien)
• Person living within the borders of a country, but is not a citizen of that country; see also

alien reciprocal operation

See

alkaline Most popular type of non- (there are some rechargeable ones, too) that offers a higher energy density and longer shelf life than do carbon-zinc batteries, but at a higher cost; see also

alkaline batteries

alligator

Slang for a , especially a , that seems to transmit farther than it could receive a signal (think big mouth, little ears); see also

allocated / allocation

See

AllStar

Software-based system that radio around the world through your cell phone or other computing device using Voice over IP; see also and the

alpha

parameter (also known as common-base current gain, symbol α) defined as the change in collector with respect to emitter current; see also and

alphabet

See

altazimuth

See

AM

• Short for

amateur

• Person who is to a for communication within the spectrum, often synonymous with ; i.e., a ham operator
• Practitioner, hobbyist, or promoter who is not paid for performing a particular service
• Short for one or more of the to , as in amateur bands

Amateur Auxiliary

American radio organization consisting at one time, of and now , and operated by the , working in conjunction with the to in the US to help self-police their compliance with rules; see also and

Amateur Extra

Highest level radio obtainable in the US and some other countries, whose privileges cover all of all , and that certifies the as one having a much greater understanding of regulations, operating practices, and electronics than that of a class licensee; see also

amateur operator

See

amateur radio

Type of operation or service, distinguished from , , and radio, and implies that the is not paid for radio services; typically synonymous with radio; see also and

amateur radio band

One or more continuous ranges assigned or allocated to the ; see also
Note: the term does not guarantee exclusive use of a , since some bands are allocated on a primary basis and others on a secondary basis

amateur radio club

Organized group of people (also called amateur radio society) who have (at least) as a common interest, whether or not the individuals are (because, for example, they're related to a ham or know one); see also ham radio clubs and ARRL-affiliated club search

Amateur Radio Emergency Service Corps of trained volunteers organized to assist in public service and ; see also and

amateur radio operator

Person who is a of an or is as such; see also

amateur radio satellite

placed in orbit to serve (at least) purposes; see also and

Amateur Radio Service

See

amateur radio society

See

amateur radio spectrum

Collection of that are for use by the

amateur radio station / amateur station

See

ammeter Instrument that measures electric by connecting it in series with the circuit, and is usually one of the functions found in a ; see also and

DC ammeter

amp

• Short or abbreviation for
  There are 2 amps flowing through that
• Short for
  My amp is starting to get warm

ampere / amperes

The basic unit of electrical (often shortened to amp) and represented by the symbol A; see also

amplifier

• Device or circuit that outputs a signal that is identical to, but increased in intensity of, its input signal, the ratio of its output to input strength referred to as the amplifier , expressed in ; see also and
• See
• See

amplifier tuning pulser / amplifier tone pulser

Device or circuit (also known as tuning pulser, tone pulser, and woodpecker, or simply, pecker) that aids in tuning a on output by sending it a rapid stream of pulses at a low (whose pulsed sound resembles that of a woodpecker), to provide sufficient , without placing excessive stress (over-heating, -over) on critical components, thereby preventing premature and possibly costly failures, by keeping the output relatvely low

amplitude

Magnitude of (electrical or ) signal strength; see also

amplitude modulation Method of combining an information signal (your , , , etc.) with an signal of constant (the ), so that the amplitude of the output signal varies with the information signal; see also and

AM waveform © HamRadioSchool.com

AM spectrum

AM radio

• Nickname (also called AM broadcast and AM band and ) for the portion of the that is dedicated to , which in the US spans 530 kHz to 1700 kHz, using 10 kHz spacing; see also
• Nickname for an

AMSAT

organization (officially Radio Amateur Satellite Corporation) that designs, builds, arranges launches for, controls, and maintains satellites with payloads, including the series of satellites; see also

AMTOR

amateur teleprinting over radio : once fast-growing and pioneering transmission that was an improvement over by using , , and , but is rarely used today; see also and

AMU

analog / analogue

Type of circuit or signal whose operational levels vary continuously with time, such as that of an (op-amp); see also

analog radio

Communication by transmission and reception of an signal by using an ; see also

analog-to-digital converter

Device or circuit that converts an signal to a digital one by creating a digital value that represents each amplitude; see also

analyzer

• See
• Any physical instrument or software that performs tests on a device or signal to determine properties, characteristics, or functional integrity

ANC

active noise control or automatic noise cancellation : technique (also called active noise reduction) for reducing or suppressing unwanted in a signal by introducing a second signal; see also

ANCS

assistant net control station : the or person who assists the with control responsibilities

Anderson connector / Anderson Powerpole

See

AND gate Digital logic circuit () in which all its logic input signals must be asserted ("TRUE", high, or 1 state) to produce an asserted ("TRUE", high, or 1 state); see also

AND gate symbol

Andrew coax / Andrew cable / Andrew Heliax

See

ANF

automatic notch filter : circuit that, when enabled, performs the function of a by removing (filtering out) any continuous signal that might be present in the

angle modulation

Process of varying () the of a sinusoidal wave to transmit information, of which and are two types; see also

angle of radiation

Angle (often called takeoff angle), with respect to level , of the strongest or average field delivered from an ; see also

ANL

anode

Positive terminal or of a device or component, into which flows; see also (and )

ANR

ANT

antenna Device that converts electrical into and vice versa; a piece of equipment by which radio waves are transmitted and/or received Some antenna types and Some antenna categories Criteria antennas See also

ham radio antenna

antenna symbol

antenna analyzer Device that measures and characteristics, such as , , and ; see also and

antenna analyzer

antenna aperture

Area (also called effective area, capture area, and receiving cross-section), oriented perpendicular to the direction of an oncoming , that would intercept the same amount of from that wave, as is produced by the receiving it;see also

antenna array Multiple installed or configured so that the combination results in a unit that exhibits greater and than each might otherwise realize on its own; see also

antenna array

antenna coupler

See

antenna current

See

antenna discharge unit

See

antenna effective aperture / antenna effective area

See

antenna efficiency

Ratio of the total power radiated by an with respect to the net power input to the antenna, equal to the ratio of the antenna's to its total (ohmic plus radiation) resistance, often expressed in or as a percentage; see also

antenna element

See

antenna farm Location dedicated to the placement of (usually many) and TV ; see also Geographical location, with established boundaries, in which structures with a common impact on aviation may be grouped, as defined by of the rules, ; see also ; of the same Part

antenna farm of JH4UYB

antenna feed

See

antenna gain

Ratio of the quantified tendency of an to focus more of its radiated signal strength or reception ability in one direction than that in other directions, often expressed as a ratio of the radiated signal strength of the antena in the direction of maximum radiation to that of a (another way to look at it is the ratio of the amount of required by an with respect to the amount of power required by a particular to produce the same field strength at a point, expressed in , or the ratio of the amount of power required by a with respect to the amount of power required by a particular antenna to produce the same field strength at a point, expressed in ); see also

antenna match Fixed (non-adjustable) device or circuit that modifies () the of the to that of the and/or by presenting a complex conjugate of the antenna impedance, and often achieved by an ; see also

antenna (gamma) match

antenna mount

Device used to connect or install an to a fixture, such as a , a building, or a vehicle, and includes such types as and

antenna party

Event in which people gather to help erect an , especially a or large

antenna pattern / antenna radiation pattern

See

antenna position indicator Also called azimuth indicator, position indicator, rotator controller indicator, rotator display, device that displays the (position bearing relative to north) of a , visual part of (often built into) an

antenna position indicator

antenna rotator / antenna rotor Device that changes the aim of a by rotating the assembly; see also

antenna rotator

antenna rotator controller / antenna rotator control unit / antenna rotor controller Electrical device that changes the aim of a by sending signals to a attached to the assembly

antenna rotator controller

antenna switch Device (also called coax switch and antenna selector) that allows connection between the and that for any one of several , or between an antenna and one of several transceivers

antenna switch

antenna system

Collection of components and interconnected devices that support the delivery and conversion of an electrical signal into an field, or reception of an RF field, for conversion into an electrical signal, often including but not limited to a , , (including , , , and ), , , , , and associated (can also include a and an meter, but does not typically include an or )

antenna tower Self-supporting structure used to support one or more , and/or other equipment; see also

beam antenna atop an antenna tower

antenna trap

See

antenna tuner Adjustable device (also known as an antenna tuning unit or antenna coupler or feedline coupler or matchbox or transmatch or in the UK antenna matching unit) that the of the system with that of the to maximize transfer from the transmitter to the antenna; see also and

(manual) antenna tuner

antennae

Outdated plural for ; more than one antenna

anti-aliasing filter / anti-alias filter

circuit that prevents or reduces the (usually) undesirable effect known as aliasing, which is the construction of a false (an alias) signal from a sample of the original signal, usually the result of under-sampling; see also and

anti-VOX / anti VOX

circuit or feature used in to prevent audio from the speaker from actuating the voice-operated ; see also

aperture

See

aperture efficiency

Ratio of the quantity of electrical energy produced by an to the quantity of signal it received; measure of the of an antenna's ability to convert its received signal (that encountering its physical ) into an electrical signal (not precisely related to ); see also

A_P-index

See

apparent power

See

appliance operator

• Typically derogatory term for an operator who possesses little desire to , tinker with, or repair equipment, or one who has little motivation to increase understanding of internal radio equipment operation or radio theory above what the examination had required; so-called because the person is content with operating a piece of equipment (appliance) that was secured to perform a specific function
• operator who frequently relies on others to configure or repair equipment due to disability or because of unfamiliarity with the controls or settings

APRS

: digital communication () for exchanging information among a large number of radio covering a relatively large area; see also and

AR

for the end, to indicate the end of a formal ; see also

ARC

arc-fault circuit interrupter / arc fault circuit interrupter Type of fast-acting or receptacle (outlet) designed to shut off electric in a circuit when it detects an occurring in its circuit; see also and

AFCI outlet and breaker

arcing / electrical arcing Electrical breakdown of one or more gases to produce a plasma discharge, caused by electric current flowing through air, which is normally non-conductive; at one time called voltaic arcing; see also Note: arcing can also occur in a vacuum, but vacuum arcing is due to a slightly different set of circumstances

arcing between wires

lightning, a form of arcing

ARDF

AREDN

ARES

arial

You likely meant aerial, as in , not the

ariel

You likely meant aerial, as in , not the

ARISS

Amateur Radio on the International Space Station : program that allows radio on earth to communicate with astronauts aboard the for educational purposes; see also

ARL number

See

ARO

ARQ

automatic repeat request or automatic repeat query : technique for controlling transmission errors by requesting a re-transmission of the same data; see also

array

See

arrester / arrestor

See

ARRL American Radio Relay League : non-profit association of enthusiasts, and the primary representative organization of amateur radio to the US government; see also

ARRL radiogram

Formalized message composed for transmission, as part of the program; see also
• radiogram template

ARRL radiogram number

Shorthand code (often abbreviated ARL number) that represents words, phrases, or sentences optionally used for composing formal written ARRL radiograms, as part of the program; see also

ARRL Section Any one of the American and Canadian geographic areas, as defined and designated by the ; see also and

ARS

artificial ground Device or circuit that presents an reference or in the absence of an actual connection, to allow an to be above ground level (such as on a tower or multi-story apartment building), for example Device or circuit (also known as a virtual ground) that maintains a reference at a specific point in the circuit without being directly connected to the actual point; see also

artificial ground

ARTS

Auto-Range Transponder System : automatic polling and reporting system in which multiple communicate with each other through a (handshake) that helps one transceiver determine whether other similarly equipped transceivers are located, within a predefined physical proximity sufficient for reliable communication, found primarily in transceivers, but supported in Motorola, TYT, and other radio makes as well

AS

for stand by, to indicate the directive to wait or pause; see also

ASCII

American Standard Code for Information Interchange : seven- or eight-bit code for representing text characters in computers, text-based communication equipment, and transmissions; see also

ASK amplitude-shift keying : low-rate transmission that combines with ; see also

ASL

above sea level : height or elevation measured with respect to the historic mean sea level; see also

astable multivibrator

Circuit whose signal continuously alternates between two states without an external clock (also known as an ) and can itself function as a clock circuit; see also

asymmetric goniometer control

See

atmospheric noise

Radio noise that originates from natural atmospheric processes, primarily lightning discharges in thunderstorms; see also and

ATNO

all-time, new one : short for with which is made for the first time (often referring specifically to a contact)

ATS

ATT

control on a , reducing the strength of the incoming signals, allowing stronger signals to be heard better over the

attenuation / attenuate

• Reduction in signal strength, either electrical or , and sometimes referred to as negative ; see also
• Rating of an electrical conductor by its ability to reduce the strength of an applied signal, due to its physical characteristics, such as and geometry (length); the potential (possible) reduction of a proposed signal by a specific quantity
Note: attenuation and loss can often refer to the same effect, of signal reduction or conductor rating of potential signal reduction, but technically, attenuation is signal strength reduction, while loss is wasted signal strength

ATU

ATV

amateur television : video and (, also known as fast-scan television) transmissions made on , usually on the , , and , in that order by popularity; see also and

audio

• Audible () sound, which is and by one , then and by another, to reproduce the audible sound
  A is well-suited for demodulating signals to generate the audio
• Sound quality or level (volume)
  Your audio is very loud, but has a lot of

audio check / audio report

for (report on) sound quality, such as loudness, understandability, , background (such as , , and ), echo, distance from the whether you're or , or are using sufficient ; see also and
This is KNØJI...may I please get an audio check?

audio frequency Acoustic (non- mechanical vibration) range audible to the human ear, encompassing roughly 20 Hz to 20,000 Hz; see also

audio FSK

See

aurora Visible natural phenomenon resulting from the interaction between charged particles in the and the (primarily the ), where the earth's magnetic field has deflected the particles toward the regions surrounding its magnetic poles, the display near the north magnetic pole called Aurora Borealis (northern lights) and the one near the south magnetic pole called Aurora Australis (southern lights); see also Type of made possible by reflecting off the charged ceiling produced by an aurora (auroral ), resulting in a fluttery or raspy sounding signal, making possibly the best of communication applicable to this phenomenon; see also

Aurora Borealis

auroral-E / auroral E

Type of that occurs as are off the near the earth's magnetic poles, normally during the time of day as auroral activity begins to diminish

authorized emission

Transmitted signal of a , , , and that is permitted to an operator holding an appropriate ; see also and

automatic control

Type of control in which the is not physically at the and not actively manipulating the station controls, such as operation (when the operator begins actively manipulating the controls, the control type becomes )

automatic gain control

Self-controlling circuit that attempts to maintain a constant level of output by automatically adjusting the of the input signal; see also

automatic level control

Self-controlling circuit that attempts to maintain a constant level of output by automatically adjusting the of the to prevent it from overloading, thereby reducing and the chances of possible physical damage to the due to excessive

automatic link establishment

for (without assistance) initiating and sustaining communication, to provide a rapid but reliable contact between in spite of changing , reception , and congestion; see also and

automatic noise limiter / automatic noise-limiter / automatic noise limiting

Circuit that reduces wide-band (often ) impulse and peaks by limiting their amplitude (sets the level) according to the incoming signal strength, thereby reducing receiver reaction to amplitude variations and pulse noise; see also
Note: because the two are often confused, ANL filters the unwanted signal by limiting amplitude while NB filters it by attenuating the signal for the duration of the noise

automatic repeater shift

Technique that allows a to automatically set the shift () and for a manually tuned , with assumptions based on a local (national)

automatic transfer switch Electrical device that automatically the path of electrical from one (typically ) to another (such as or generator) without manual intervention; see also

autopatch / auto patch

Interface between a and the local telephone (also known as a phone patch), allowing you to make regular phone calls from your radio by the use of tones; see also and
Note: one type of autopatch, known as autopatch (or simpatch) is implemented through a non-repeater connected to the local telephone service

auto repeater

See

autotransformer

Electrical that contains a single winding and is used in many distribution applications; see also

auto tuner / autotuner / automatic tuner Type of that requires little user-intervention to perform the functions; see also

auto tuner

AUXCOMM

Auxiliary Communications or Auxiliary Emergency Communications : intense, multiple-day training course by the Department of Homeland Security that augments local communication types that include, but is not limited to, ; see also

auxiliary power connector / auxiliary power plug / auxiliary power socket Type of (often called a cigarette lighter plug or cigarette lighter socket) that is found on most vehicles and many and banks; see also and

cigarette lighter plug and socket

auxiliary remote base

See

auxiliary station

that controls another station over a ; see also and

AVC

automatic volume control : former name for

average power

• Also called mean power, the total amount of energy expended, dissipated, absorbed, transferred, or required in a given amount of time, or P = Δ E / Δ t; see also
• Quantity of in an circuit

AWG

American wire gauge
• American standard for diameter, size, thickness, or -carrying capability of wire and other materials; see also
• American designation (also abbreviated gauge) for the diameter, size, thickness, or -carrying capability of a particular electrical wire model, as in 12 AWG

AX.25

Amateur X.25 : designed for and used by to transmit and receive frames that contain (location information); see also
• (as it applies to APRS)

az-el / azel azimuth-elevation : description (also called altazimuth) of an or other equipment that is capable of aiming an not only radially but also up at an angle toward the sky, useful in activities such as , , and communication; see also

az-el rotator shown on a satellite antenna mount

azimuthal / azimuth Radial appearance of something as it is viewed from above; for example, an azimuthal of an is its transmission strength pattern as seen looking down on it from above the antenna; see also and and Angular measurement (typically number of degrees) from north toward a target bearing in the clockwise rotational direction; see also

an antenna's azimuthal radiation pattern

azimuth indicator

See

backlash current

See

backscatter / back scatter

off the , often received on a above the ; see also and

bacon frying

See

bad solder joint

See

bail-out bag / bail out bag

See

balanced feedline / balanced feed line / balanced line

Pair of electrical conductors, both of the same size, shape, and material (and therefore the same ) their entire lengths, whose chief advantage is rejection, and of which , , and twisted-pair are examples; see also and

balanced modulator

Circuit whose input is a signal and the signal, and whose output is (the two sidebands without the carrier); see also

balanced tuner / balanced-line tuner

Type of whose symmetrical output circuit presents conductors with identical impedances with respect to , meaning they appear as though they contain separate tuning circuits for each conductor, but are adjusted in parallel, to ensure equal impedance presentation; see also

balun Type of inserted between a (such as ) or (such as a ) and an (such as ) to either provide an () between the two, or to function as an () to prevent the feed line from radiating (or both); see also and Transformer-less device that simply connects a balanced device with an unbalanced antenna, or vice versa Type of inserted between the and the , or between two lengths of the feed line

current balun

balun cutaway

banana plug Type of single-wire that is a single protruding rod with spring metal that applies outward pressure against a smooth, cylindrical metal receptacle; see also and

banana plugs

band One or more sets of continuous within the that have been by the or for communication purposes by specific groups, such as , or specfic uses, such as ; see also the FCC Amateur Radio Frequency Band Allocation Chart [PDF] for all and Note: the term does not guarantee exclusive use of a band, since some bands are allocated on a primary basis and others on a secondary basis

band allocation chart

band conditions

Atmospheric (weather, etc.), , , and other activity that in concert affect for a particular

band-pass filter / bandpass filter / band pass filter Circuit or device that out most or all signals of outside a particular , thereby allowing only signals within the to pass through the device, useful for and other applications that require receiving or transmitting within a relatively narrow frequency range; see also

band-pass filter graph

band plan

Voluntary of a , usually specified for a particular geographical location, to avoid between incompatible ; see also and

band-reject filter / band-stop filter / band reject filter / bandstop filter Circuit or device that out most or all signals of within a particular , thereby allowing all signals except those within the to pass through the device, useful for the removal of an interfering frequency such as the signal; see also

band-reject filter graph

band scope

See

band segment

See

bandspread / / band-spread / band spread Mechanical or electrical fine-tuning control on older (, obsolete) and whose primary is very coarse for the size; see also Granularity (resolution) of required to select a single on a particular (how close together the seem to be); see also Note: bandspread typically refers to a signal condition, whereas selectivity typically refers to a device's ability

vintage receiver with bandspread tuning control

bandstop filter / band-stop filter / band stop filter

See

bandwidth

• Absolute value difference between the highest and lowest you are using or occupying; see also
  ("Absolute value" is specified because, for example, a signal might be split, such that it occupies 1821 kHz through 1824 kHz, and 1826 kHz through 1829 kHz, making 1829 − 1821 = 8 kHz.)
• Continuous range of being used by a particular transmission or piece of equipment
  Many transmissions are limited to a 12.5 kHz bandwidth
• Continuous range of for use in a particular
  The section of the has a bandwidth of 60 kHz
• Difference between the upper and lower limits of a or other circuit ; see also

barefoot

Slang for without an
I was able to Japan barefoot

base station that is typically too large to be normally carried around by hand or installed in a vehicle that is installed in a home or other fixed location, regardless of transceiver size or facility type; see also (also called fixed station) that is established in a permanent structure with equipment not intended for operation; see also

base station transceiver

baseband / base band

• components present in the signal (in other words, the original unmodulated signal); see also
• of an signal

battery electrical energy consisting of one or more electrochemical cells that convert stored chemical energy into electrical energy; see also

batteries

battery symbol

battery management system Electronic maintenance device or apparatus that monitors, reports, and controls the parameters of a , to protect the battery from damage; see also

battery management system

battle box / battle-box

See

batwing antenna / bat-wing antenna Variation of the normal , in which the are shaped into a characteristic butterfly, bowtie, or bat-wing shape, often used to cover a large by ; see also

batwing antenna

baud

• Number of symbols transmitted per second, also known as symbol rate; see also
• Modulation rate of transmission, expressed in bits per second

Baudot code

Outdated 5-bit code for representing text characters in teletype and other text-based communication equipment; see also

bayonet

Common (with many light bulbs, data cables, CD packaging spindles, and camera lenses) fastening mechanism used by some connectors, such as , characterized by a push-and-turn attachment method; see also

bazooka antenna

See

BBHN

BBTD

BCB

BCI

broadcast interference : originating from a or and picked up by an because of or

BCL

• broadcast listening : hobby of listening to primarily for informational or entertainment purposes
• broadcast listener : outdated term for a person who participates in broadcast listening

beacon

• that transmits information about and , and can be used to test equipment, perform experiments, and observe and reception ability; see also
• used or automatically enabled during a time of distress or , to alert others (especially , military, or other emergency personnel); see also

beam antenna Type of that possesses high transmission and reception performance in one or more particular directions (property known as ) while exhibiting relatively large reduction from other directions; see also and

beam antenna

beamwidth / beam width Angle between the half-power (-3 ) points on the main lobe of an 's , also called the half-power beamwidth; see also

azimuthal antenna pattern showing approximately 34° beamwidth

beat frequency oscillator

Circuit or device in a that converts (by re-inserting the missing signal) and signals to (see ); see also

bending

See

BER

• bit error rate : number of received data stream bits per second unintentionally altered due to , , , or bit synchronization errors, often expressed as a percentage; see also
• bit error ratio : ratio of the number of received data stream bits unintentionally altered, to the total number of bits transmitted, often expressed as a percentage

beta

parameter (also known as common-emitter current gain, symbol β) defined as the change in collector with respect to base current, and is the parameter most commonly associated with transistor (ability to amplify a signal); see also and

Beverage antenna Type of very long and low directional receiving made primarily for and and is characterized by its large size, often extending for miles and has comprised some of the world's largest continuous antennas, but is not typically used for transmitting due to high compared with that of other antennas; see also

modern 160-meter Beverage antenna, about 280 m in length

diagram for a Beverage antenna about 6 feet above ground and at least 1 wavelength long

BFO

BFSK

binary frequency-shift keying : low-rate transmission in which the signal is shifted between two to convey the information, in which a 1 is identified by the frequency and a Ø is identified by the frequency; see also and

BiCMOS bipolar complementary metal-oxide-semiconductor : logic family that uses both and , to offer the high input of CMOS and the low output impedance of bipolar transistors; see also

BiCMOS internal schematic

bilateral agreement / bilateral arrangement / bilateral operating agreement

Set of rules agreed upon by two countries to authorize radio operation in one or both countries by a person who is not a citizen of ( to) one or both countries

billboard antenna

See

bipolar junction transistor

characterized by low input , using emitter, base, and collector , and whose flow characteristics are determined by the contacts of different materials in the device; see also

bird

Slang for satellite, especially one used as a radio ; see and (unrelated to the BIRD satellite )

birdie / birdy

Slang for a phantom (false) chirping or that is produced by a being to a that is a multiple of the output frequency of one of its own (an undesirable product of a or similar), and can often be hidden by increasing the level

bit rate / bitrate

Speed of transfer, expressed in bits per second (symbol bit/s and often the non-standard symbol bps), quantifying the number of information bits transmitted per second; see also

BJT

black hole

See

bleeder resistor that is connected in parallel with the output of a high- to discharge the energy stored in the supply's , improving output voltage when the supply is on, and to bleed off the remaining electric charge when the supply is off, to allow for safe handling; see also

schematic showing bleeder arrangement

bleed-over / bleed over / bleedover / bleeding

Type of in which a transmitted signal of one is strong enough to be received at another (relatively close) frequency, potentially resulting in a disruption of the received signal; see also
Note: the term "ACI" (adjacent-channel interference) is not technically identical to bleed-over in every use case, but is provided as an example, since bleed-over can occur within the same channel (see also )

blind zone

See

block diagram Drawing or other visual aid containing boxes, figures, or shapes to graphically display the high-level interconnection, interdependency, or interoperability between the or other major functional sections of a device or system; see also

transceiver block diagram

blocking dynamic range

Difference in between the and the level of an incoming signal that will result in of

BMS

BNC bayonet Neill-Concelman : model name for a common quick connect / disconnect 50 Ω or 75 Ω gendered used in and applications; see also Note: that BNC stands for "bayonet Neill-Concelman" is widely accepted but questionable, largely because Paul Neill developed the BNC connector before Carl Concelman became a co-worker

BNC connectors

boat anchor / boatanchor Slang for a heavy, old (, antique, obsolete) that's typically powered by () for its internal , which lends to its extra weight; see also

Hallicrafters boat anchor

Heathkit boat anchor

bobtail curtain

See

bonding

Practice of electrically connecting all exposed metallic items not normally designed to carry electric in a room, building, or system, as a protection from electric shock by ensuring they are at the same electric potential, particularly potential if possible; see also

boom Rigid crossbar, , or other member for supporting the weight, shape, and placement of the , , and other , along with any other component necessary for the design and function of the particular antenna, and can be either conductive or non-conductive, depending on element placement

vertical Yagi antenna showing its elements held in place by the boom

boom placement with respect to Yagi elements

booming

Slang for clear and very strong signal; action of sounding or better
This guy was booming from Ohio on

bootleg

Older slang that describes some sort of illegal (indicating intentional) activity involving radio; see also and
• bootleg : describes illegally modified equipment or illegal radio operation
• bootlegger : person who operates on an either without an amateur or uses a call sign not belonging to the operator
• bootlegging : operation on an without an amateur or operation of a radio station containing illegally modified equipment (once applied primarily to operation)

bottle

Older slang for
I'm using a three-bottle

bounce back / bounce-back / bounceback

CB slang for a configuration of two-element , often mounted on a vehicle, and sometimes used for competitive operation

bowtie / bow-tie

See

BPF

BPSK

binary phase-shift keying : low-rate transmission that uses to shift between two of an signal to convey the information, and at one bit per symbol is the simplest form of ; see also

braid / braided strap

See

brass pounder

Older slang for who uses a instead of a or to send

break

• Announcement of great urgency, formerly (unfortunately still common) used to request entry into a current
  Break! Break! Break! This is an ; all will please clear this
  Note: the ARRL discourages using the word break except during an emergency (click Joining a Conversation in Process)
• Pause between

break-in / break in

Attempt to transmit during a brief pause between two or more separate transmissions by others (or another), to have your transmission acknowledged by one of them

breakdown voltage

Minimum reverse applied to a or to cause the component to conduct in the reverse direction; see also

breaker

• See
• CB slang for an announcement by a transmitting operator who wants to start a conversation
• CB slang for a who wants to join a conversation in progress

breaker panel / breaker box

See

breaking squelch / break squelch

Action of un-muting the while an incoming signal's strength exceeds the squelch threshold

breaking station

that is attempting to join () a conversation in progress

bridge circuit Electrical circuit in which two circuit branches, typically in parallel with each other, are connected (bridged) by a third branch connected between the first two branches at some intermediate point along them, to measure a null (zero volts), which confirms an between the two branches; see also

bridge circuit

bridge rectifier

See

broadband butterfly terminated dipole antenna Adaptation of the , (sometimes butterfly antenna) with its elements formed into two equal and opposing triangles, lending itself to improved stealth and slightly greater over that of a typical

Broadband-Hamnet

See

broadband noise

As it applies to (as opposed to audio), type of (also once called RF hash) that exhibits unusually large or that is experienced in many ranges over an unusually large spectrum

broadband terminated dipole antenna

Adaptation of the , with the added ability to deliver a signal effectively across a wide , some reportedly across much of the spectrum

broadcast

• Type of communication that is meant to be transmitted to the general public, also known as broadcasting; see also
• Transmit to the general public; making a one-way communication intended for the general public
• Classification of communication intended for a general audience, such as public , , and

broadcast band

Any one of many ranges in the for (and can also refer to , , other types of) communication; see also

broadside / broad-side / broad side

Side of an object presenting the greatest amount of surface area, such as flat-facing sides of a , rather than its ends

broadside array

Classification of , in which multiple work in tandem (in- or out-of-phase) to produce a with exhibited from its

BT

for end of paragraph, to indicate the end of a thought, idea, or thread, and the beginning of the subsequent one; see also
Note: the code for BT is exactly the same as that for an equal ('=') sign

BTH

beyond-the-horizon : see

buck converter

Circuit that converts a to that of a lower DC voltage value (the word buck being slang to lower and the opposite word boost being slang to raise), and is often an integral part of a , but can also be obtained as a stand-alone product; see also

bug Slang for a sideways-motion semi-automatic and non-electronic telegraph made for high-speed transmissions; see also and and

Vibroplex bug

bug-out bag / bug out bag

See

bullet connector

See

bureau

Short for

BURO

(confirmation message forwarding service); see also

bus Electrical conductor (often misspelled buss or bussbar) that provides multiple electrical devices a common connection or pathway, and is often un-, but sufficiently heavy compared with the conductors that attach to it; see also ground bus : thick, heavy plate or bar (busbar) that provides a common connection point for the of multiple pieces of equipment, and that is typically with power bus : single, relatively large conductor (distribution block) that provides (sufficient at the intended ) distribution to multiple devices (some distribution blocks provide both positive and negative sides to devices)

ground bus

power distribution block with both a positive bus and a negative bus

business band

See

buss

misspelling for

busted call

Slang for a entry that was entered incorrectly, usually during

busy lockout / busy channel lockout

feature, in which the ability to transmit is inhibited if a signal is detected on the currently selected , even if the is by a , in an effort to prevent accidental

butterfly antenna

See

BW

BZ / B sub Z Direction and strength of the component that is perpendicular to the ecliptic plane, with a southward indicating an increased likelihood that incoming solar particles will cause disturbed conditions, such as

IMF diagram showing BX, BY, BZ components

C

• for (correct)
• signal or unstable signal, when added to an report; see also

CØG / C0G

See

C4FM

continuous 4-level frequency modulation : transmission standard created by using at two bits per to create its four states; see also

Cabrillo

Text file format standard for radio targeted for submission or simple record-keeping; see also

California kilowatt

Older slang for magnitude of transmitting that exceeds the

call

• Short for
• Raise or attract the attention of a particular or any listening station
  I'll take a turn calling while you do the logging

call district

See

calling area

See

calling frequency

General (of which a is one) that is recognized across the US by a gentleman's agreement for incidental use, requesting non-urgent assistance, true , testing, and whose use in making casual or first-time is encouraged; see also , which includes some calling frequencies, and a chart of amateur calling frequencies [PDF]

call sign / callsign

Unique combination of letters and decimal digits assigned to a for identification, in the format XXNYYY for the US, of which XX is one or two letters, N is a decimal digit, and YYY is one, two, or three letters; see also
• call sign rules on W5YI

call sign area / call sign region

Geographic area (also called calling area) defined by the organization overseeing the of its , which in the US is identified by a single numeral, 0 through 9, in the of each of its licensees whose address is registered within that area
Note: 'call district' is promoted by as a synonym, but is not a widely accepted term

call sign trustee

See

candy store

Slang for a store or dealer that sells radio

cans

• Slang for
• Older slang for

CAP

Civil Air Patrol : civillian auxiliary of the US Air Force made of volunteers focused on and operations from an aviation perspective, and much of which involves communication; see also and the main

capacitance

Property of a device that defines its ability to store electrical energy in an electric field to oppose changes in the across it, expressed in farads (symbol F); see also

capacitance hat Device (also known as a capacity hat or roof capacitor) that complements or counteracts the of a for an electrically shortened (typically ) by presenting a roof capacitance

capacitance hat

capacitive coupling

Also known as AC coupling, effect of two or more conductors not connected to each other being close enough to allow an present in one conductor to result in an AC voltage at the others, with respect to signal ; see also

capacitive reactance

Imaginary quantity of opposition to flow in a circuit () due to , that varies with and is expressed in ohms (symbol Ω) and defined as = 1 / ωC, in which C is the capacitance and ω is the frequency in radians (ω = 2πf, in which f is the frequency in Hz); see also

capacitive time constant

See

capacitive top-loading / capacitance loading / capacity loading

See

capacitor Electrical component (formerly condenser) that resists changes in the across it and stores energy in an electric field; usually contains two electrical conductors separated by a non-conducting ; see also and

assorted capacitors

capacitor symbols

capacity hat / capacity top hat / capacity top-hat

See

capture area

See

capture effect

Phenomenon of a demodulating the stronger of multiple received signals and completely suppressing the weaker ones; see also

car-to-car

See

card checker

Person who is authorized by the to verify that the made by a US toward an award (such as , , or ) are authentic, according to the collected by the candidate; see also and

Carolina Windom antenna Type of () that uses a portion of its as a , typically resulting in a lower angle of radiation than that of a plain Windom antenna

Carolina Windom antenna diagram

carrier

signal that is with an input signal, such as your , to produce a signal prepared for transmitting; see also

carrier delay

• Amount of time (also called hang time and drop-out delay) a continues to transmit a signal after the sending has , typically in number of seconds
  The hang time on that repeater is pretty long
• Time period between the moment when the sending has and the has terminated its transmission, during which the repeater might transmit a or system information
  I heard somebody during the repeater's hang time

carrier shift

Digital technique (also called carrier frequency offset) in and , in which the is shifted slightly toward a higher or lower frequency to represent a binary digit; see also

carrier squelch

Muting () of a 's (less often called noise squelch) when no signal is being received at the selected with at least the signal strength for which the squelch level is set; see also

CAT

Computer Aided Transceiver : standard created by (formerly Vertex) to provide a serial interface between a computer and a that supports the , to control functions such as , , , and setting memory

cathode

Negative terminal or of a device or component, from which flows; see also (and )

cathode-ray tube / cathode ray tube whose emits a stream (ray) of electrons (negatively charged particles) onto a phosphorescent screen to display images; see also

cathode-ray tube

cat's whisker / cat's whiskers / cat whisker / cats whisker Adaptation of the , in which the active spread out radially from a central point, rather than parallel to each other Type of , in which the looped are spread out by non-conductive spacing rods that resemble a cat's whiskers when viewed Thin conductor of the side of a , especially that of a crystal detector in a

cat's whiskers antenna

diode showing cat's whisker

cavity filter Type of that exhibits high and stability, used mostly in to prevent transmitting to, or receiving interference from, other nearby repeaters and sources, and are typically implemented as or type; see also

band-pass cavity filters

cavity filter diagram

CB

CBR

CBRS

See

CCD

CC&R / CC&Rs / CCRs

Covenants, Conditions, and Restrictions : set of rules that dictate the conditions under which you can occupy a home, which conditions might include the prohibition of, or limitations on, the installation of radio or other related equipment, and often enforced by a local ; see also

CCW

counterclockwise or counter-clockwise : negative angular direction when measuring the of an or a space object (such as a or ); see also

center-fed Zepp antenna / center fed Zepp antenna / centerfed Zepp antenna

See

center insulator Non-conductive support component to which the two and the of a are connected, but can be used for other antenna types as well

dipole center insulator

center tap

See

centi

Prefix, or units modifier, to indicate ÷ 100 or × 10^-2, and is often abbreviated c

CEPT

: agreement between the US and European nations to allow an American to operate legally within participating countries without a special or permit; see also and

certificated / certification / certified

Formerly type-accepted and type-acceptance, as it applies to a , indicates Certification or Declaration of Conformity for meeting certain requirements to legally transmit outside the (simply put, all radios, and some types of radio support equipment, such as , must be type-accepted or certificated for an to use them to legally transmit outside the amateur bands); see also

CFA

crossed field antenna : controversial type of compact-sized intended to exhibit the same as conventional antennas; see also

cfm

Short for confirm

channel / channelized

Organization of a or continuous set of that are accessible at a specific, pre-defined subset of those frequencies, known as channels, and often assigned alphanumeric designators (channel 13, channel A5, etc.); see also

Channel Guard

See

characteristic impedance

Quantity of opposition to flow () in a dependent on the line's physical properties and geometry (its characteristics), but not its length; see also

charge controller Electrical device that controls or limits the rate of electric through a , to prevent overcharging, and can protect against overvoltage, which can reduce battery performance and lifespan; meant primarily for applications, but can be used for others; see also

solar charge controller

charge-coupled device / charge coupled device

Electronic device that uses a combination of and digital circuitry to sample, convert, and store a numerous array of electric charges into digital signals, often used as an image detector in a digital camera; see also

Charlie

See

chasing DX

See

chassis

Typically metallic enclosure or frame of an electrical instrument or other machine that forms the basic external shape (footprint) of the device, protects inside workings from unwanted intrusion, and shields the from potentially dangerous contact with internal components

chassis ground

Type of identified by connection between metallic frames or enclosures of various equipment, especially a , , , , and other associated devices; see also

Chebyshev filter Type of that exhibits a very sharp (steep roll-off) and a ripple in its ; see also

Chebyshev filter schematic

check

• Word count in the of a
• Last two digits of the first year in which a was , for during some
• for communication quality, as in , , or

check in / check-in / checking in

Act of participating in a by announcing your , and possibly other information, upon request by

check log / check-log / checklog

Record () of made between , especially in connection with a , but is optionally submitted only to verify the accuracy of other submissions (by confirming their contacts), and not scored for points toward any award or other achievement

checkpoint

Person who is authorized by to verify that the made by a toward an award (such as or CQ DX) are authentic; see also

cheerleading

Slang for the practice of advertising, promoting, or information about another radio 's and location to aid other stations in making many in a short period of time, which practice is generally prohibited during ; see also and

chicken band

Slang for

chicken net

Slang for a in which participants do little more than periodically (but is still useful for testing equipment, , skill, etc.)

chip / chipset

See

chirp / CHIRP

• chirp : sinusoidal signal whose increases or decreases over time, often with a polynomial expression for the relationship between time and frequency; see also
• chirp : small change in a 's each time the transmitter is , typically due to poor stability; see also
• CHIRP : free, open-source tool for an with , , and of your choice; see also the main

choke / filter choke that blocks higher- in a circuit; see also

assorted chokes

choke symbol

choke balun

See

chordal hop between two points by two or more successive through the before arriving at its destination, resulting in a signal that exhibits less loss than the same signal, had it traveled through the dense ground atmosphere twice; see also

red = chordal hop green = typical radio wave hop

Chu limit / Chu-Harrington limit / Chu-Wheeler limit

Fundamental principle, which states that its maximum is proportional to is physical dimensions, such that the smaller an antenna in relation to its intended (or ) of operation, the less its bandwidth; see also

cigarette lighter

See

circuit breaker Automatically operated electrical (often shortened breaker) that interrupts the flow of through a circuit when the current exceeds a specified rating for a particular amount of time, to protect the powered equipment in case of overload, and is typically re-usable after being ; see also and

typical household circuit breaker

circuit breaker panel / circuit breaker box

See

circuit ground

See

circuit Q

See

circular polarization Continuously rotating alignment of a signal's around the axis of directed away from the , and a signal with such an alignment is said to be circularly polarized; see also

circulator Type of that routes signals from the to the , and from the antenna to the , while preventing the signals from passing directly from transmitter to receiver, to reduce or eliminate produced by another nearby transmitter; see also and

circulator

Citizens Band

Set of 40 , low-, -free, and short-distance (typically 5 miles or less from base to mobile or 2 miles or less from mobile to mobile) (also called CBRS, for Citizens Band Radio Service); see also
• CB on CFR Part 95
• chart of assigned CB frequencies [PDF]

city power

See

civil defense

Program to protect citizens from natural and other , and in the US is now part of FEMA; see also
Note: while civil defense in the US and Europe was originally established to protect against military attack, its emphasis today has shifted to emergencies and disasters in general

CL

closing station, to indicate the is going (not technically a ); see also

clarifier

See

class

category or classification that defines the 's transmitting privileges, of which , , and can currently be earned, and Advanced and are still recognized; see also and
Note: to prevent confusion, the term course more appropriately refers to a classroom experience, even online

Class A amplifier

that is characterized by low , and therefore appropriate for amplifying signals, in spite of being relatively ; see also

Class AB amplifier

Type of that is much more than a because it operates on less than the full (greater than 180° and less than 360°) signal cycle; see also

Class C amplifier

Non- amplifier that is characterized by high , and therefore appropriate for amplifying signals, but not those of ; see also

Class D amplifier

Type of that uses switching technology to achieve high , thereby requiring less to operate, compared with that of other amplifier types; see also

Class X / Class-X

See

clear

• I hereby relinquish this frequency for others to use (does not indicate whether you actually intend to stop speaking), or to a lesser extent, I have finished speaking and am ; see also
  I'll be clear and this
• Description of a or that appears to be free of transmissions (available for use) at the moment
  Let's to a clear

climbing harness

See

clipping / clip-distortion

Form of defined by limits on a signal at a specific threshold, often caused by excessive , more applicable to than to ; see also

closed closed circuit : circuit that makes a complete flow path closed repeater : that is available for use only to a specific group or by sending an access code The 448.325 is a closed repeater

CLOVER / CLOVER-II / CLOVER-2000 / CLOVER 2000 / CLOVER-400

Series of transmission that were specifically designed for use on ; see also

cloud burner / cloud-burner / cloudburner

Older slang for

cloud warmer / cloud-warmer / cloudwarmer

Older slang for

club

See

club trustee

See

CMC

CME

CMOS complementary metal-oxide-semiconductor : technology that makes use of material for constructing in most of today's , , static memory, and many other digital logic circuits that require high-speed switching with very low consumption; see also

CMOS chip

CMOS transistor symbols

CNDX / cndx

condition or conditions, general state of and between one location and another, especially that in another country; see also
The CNDX on is favorable today

coax

Short for

coaxial antenna / coax antenna

Category of characterized by one or more of its being constructed from ; see also

coaxial cable made of an inner conductor surrounded by an layer, which is then surrounded by a conducting , all of which share the same cylindrical axis (hence the term co-axial), and used most often as a radio , the purpose of the shield to prevent of unwanted signals to or from the wire; see also chart of coax cable loss and capacity [PDF] for selected

coaxial cable

coaxial capacitor Electrical component (part of a class of called a feed-through capacitor) made of an uninterrupted wire or other conductor completely surrounded by a material, which is then completely wrapped in a cyclindrical metal sleeve, such that all three pieces share a common axis along the length of the wire; the wire at the center typically used to conduct supply in a circuit, while the sleeve is connected to , thus out high- (such as alternator noise) in the DC path; see also Note: the geometry and function of gives the appearance of a coaxial capacitor, but the capacitance of coax used in feedlines typically range in pF, while that of coaxial capacitors typically range in µF

coaxial capacitor

coaxial capacitor symbol

coax stub / coaxial stub

• Type of made from a length of for transformation in an effort to provide between an and the
• Type of made by using specific lengths of to design a or circuit to filter unwanted signals

coax switch

See

code

Short for

code plug / codeplug

Binary file that contains configuration information, plus , , , , , and other settings, for the proper operation of a particular model, and so-called because originally much of the settings (code) were hard-wired on a small device (plug) that you insert into a compatible transceiver, to perform the configuration and programming

cold solder joint Poorly soldered union of two or more electrical conductors, often resulting in an unsound connection or intermittent contact, and can have a grainy appearance; see also

cold solder joint (right)

cold (grainy) solder joint

collinear antenna Multiple arranged such that their primary radiating are positioned along a common line, to form an antenna whose is greater than that of each section alone; see also

vertical, two-element collinear antenna

color code / color-code / colorcode

• Set of multi-colored stripes or dots painted, marked, or otherwise applied to an electrical component, to represent its functional quantity value; see also
• Setting that represents a digital version of value for access, allegedly so-called because the settings were once set by physical color-coded

Colpitts oscillator circuit that achieves its generation by supplied through a divider, and is one of (at least) three oscillator circuits used in equipment, commonly in applications; see also

circuit employing a Colpitts oscillator

combiner Device or circuit (sometimes RF combiner) that brings together two or more signals (often of differing within the same ) into one signal, to be transmitted through an or forwarded to another circuit or for further processing (not to be confused with ), often used as part of a site; see also Note: a combiner can often be used as a (sometimes RF splitter), to perform the reverse function

combiner / splitter

come back

• please reply : request or demand for a response
  Come back with your
• comeback : CB slang for reply
  Thanks for the comeback

come in

begin speaking now or can you hear me?; see also

come on in

please join our conversation : CB slang for invitation to begin transmitting during a conversation already in progress

comment

• Any statement, remark, or even question made to add value or information to the ongoing conversation
  Sam made a comment on the the other day
• Announcement that you would like to interject a statement or remark related to the current discussion
  KI7ABC comment

commercial

• Type of local communication for use in corporate, industrial, or educational environments, such as construction sites, warehouse stores, mass transit vehicles, and school buses; see also
• Type of communication intended to support a business, whether for-profit or otherwise, such as a news

commercial power

See

common-mode choke

See

common-mode current / common-mode signal

Electrical behavior in a two-conductor or other such that the in one conductor is not perfectly equal and opposite that of the other conductor (also called antenna current, imbalance current, or secondary-mode current), resulting in energy produced by the difference in the currents, often the cause of radiation and ; see also ; the following articles are recommended for a better understanding of this concept, as well as :
• (good private article)
• How Common-Mode Currents are Created [PDF] (article)

companding / companded / compander

technique (named from compressing - expanding) that involves compressing an signal prior to transmission, then expanding (decompressing) it at the to improve the of the signal; see also

comparator

See

complex number

Sum of a real number and the imaginary unit multiplied by another real number, as in a + jb, with a and b being real numbers and j being the imaginary unit; see also

complex power Quantity of that is supplied to a , expressed by the S = P + jQ, in which S is the complex power (of which the magnitude |S| is the apparent power), P is the true power, j is the imaginary unit, and Q is the reactive power, resulting in the Pythagorean relationship apparent power2 = real power2 + reactive power2; in layman's terms, apparent power (expressed in volt-amperes, symbol VA) is the power you experience (see or feel, for example), and is the one that must be taken into account for circuit component capacity calculations, because it is the power input to the circuit real power (expressed in watts, symbol W) is the power that performs actual work (consumed), and so is power that residents pay for, also called true power, and active power, and is equivalent to reactive power (expressed in volt-amperes reactive, symbol VAR) wattless, non-productive power that serves no useful purpose (cannot perform useful work) because it is repeatedly exchanged between the associated magnetic and electric fields but is not dissipated (unitless value) ratio of the real power to the apparent power, which is equal to the cosine of the phase angle between the across the load and the through it see also and

compliance

Conformance by a owner in behalf of equipment and its to the safety limits of maximum human exposure to fields (determination of which is known as a compliance evaluation or exposure evaluation, and similar determination following equipment change known as re-evaluation); see also

compliance evaluation

See

compression

• See
• Technique that attempts to increase the transmitted signal's output power under poor operating conditions, potentially raising the of the received signal; see also
• technique that reduces the size of a voice signal while maintaining its sound quality

condenser

See

condenser microphone

See

conditions

See

conductance

Real component of , or quantity of allowance for flow in a circuit, expressed in siemens (symbol S) and is the reciprocal of in a purely resistive circuit; see also

condx

• conditions, general state of and between one location and another, especially that in another country; see also and
  The condx on are favorable today
• condition : short for general state of function, repair, or well-being
  My is in great condx

connection

• Electrical contact between two or more conductors
• Establishment of a (primarily ) communication pathway between two or more devices, , or

connector

Physical, especially electrical, interface that allows for manual attachment to a mating piece of hardware

For (especially ) connectors, see and and

For power, see

For other types, see (serial port) () (, also called phono)

See also

contact

• Communication established between two parties by ; see also and
  I made a contact on last night
• Outdated announcement (still used in a few isolated parts of the US) to request participation in a current or

Contestia

Type of transmission () that is a derivation of but is twice as fast; see also and the main

contesting

Competitive activity (also called radiosport) pursued by radio in seeking and as many as possible within the timeframe, , and specified by contest rules, also known as a type of radiosport; see also
• main contesting calendar page
• contesting and radiosport home

contest-style / contest style

Slang for a relatively formal operating plan (typically in reference to a or station), in which operation is organized according to a specific schedule (date, time, , ) during the event; unlike or

continuous wave

See

control grid

See

control operator

• Person (often abbreviated operator or simply op) who has access to the control functions of a and one designated by the station as the party responsible for station transmissions
• Person (known also as an ) who has access to the control functions of an station, and whose appears in the , and whose license determines the transmitting privileges of the station

control point

Location at which functions are performed

controlled

Any environment, area, or situation in which humans presumably have control over their to , including primarily the household, its occupants, and surrounding property, to ensure their 6-minute exposure levels remain within the controlled limits; see also
• FCC controlled / uncontrolled compliance document and worksheet [PDF]
• abbreviated controlled / uncontrolled compliance chart

CONUS

continental United States : lower (contiguous) forty-eight states of the US

convention

See

conversion

See

coordinated universal time

See

cootie key

See

copper strap

See

copy

understand and acknowledge, similar to ; see also
Copy / copy that (got it)
How copy? (how well did you get that?)
No copy (didn't hear it well enough to understand it)

core

See

core saturation

See

corner frequency

See

corona ball / corona ring / corona cap High-, high-, or high- conductor, usually near the termination of a or connection with another conductor, employing a curved shape to prevent localized concentration of strong electric fields and therefore undesirable ; see also Note: the end of a whip or similar antenna might be equipped with a small sphere that looks like a corona ball, but is typically installed to prevent stabbing people and other things with its sharp point

corona ball

corona rings

corona discharge Electrical discharge caused by the ionization of gases surrounding a conductor of high electric charge when the strength of the electric field around a high-, high-, or high- conductor is large enough to form a conductive region around the conductor, and presents significant energy losses, possible health hazards, and causes embrittlement of nearby insulators, but not strong enough to cause ; see also

corona discharge around a ring

coronal hole

Area in the sun's corona where the magnetic field is not strong enough to prevent a larger-than-normal quantity of charged solar particles (known as the ) from being ejected into space at high velocity, which, in turn can disturb communication when those particles reach the earth; see also

coronal mass ejection Massive burst of charged solar particles, which take 20 to 40 hours to reach earth after being discharged, disturbing and communication, and affecting other ; see also and a video

coronal mass ejection

COTA

Castles on the Air : award program for radio enthusiasts who set up transmitting (activators) in, on, or nearby historical buildings (medieval castles and fortresses in particular) or contact those who do so (chasers), in conjunction with the WCA program, to help draw attention to these sites; see also COTA-PA website

counterpoise

or network of suspended wires, cables (), or other conductive material or surface used as a substitute for earth ground in an system, functioning as one plate of a large , with the conductive layers of the earth acting as the other plate; see also

coupler

See

coupling

• Physical association or connection between two systems, to transfer energy or information between them; see also
• Electrical type or connection method
  The coupling between my and my is a

courtesy tone / courtesy beep

Audible tone or beep transmitted by a shortly after a sending has , signalling when another station can begin transmitting, and might also indicate that the repeater's has been reset

CPS

customer programming software : radio software distributed to customers for private use; see also and

CQ

calling any station, anywhere : general call to request with, or get the attention of, any listening , without regard to location; see also and
CQ CQ CQ...this is K-N-Ø-J-I

CQ <country name>

calling any station within <country name> only : general call to request with, or get the attention of, any listening within <country name>
CQ Japan...CQ Japan...this is K-N-Ø-J-I

CQD

Early distress and immediate assistance request indicator, later replaced by ; see also

CQDX / CQ DX

calling any station outside my country : general call to request with, or get the attention of, any listening outside the local area, especially outside one's own country or continent; see also

CQFD / CQ FD

calling any station participating in Field Day : general call to request with, or get the attention of, any listening that is participating in

CQ Zone Any one of 40 geographic areas of the world, as defined and named numerically by CQ Amateur Radio for the purpose of obtaining specific awards, such as ; see also CQ Zones of the World map

craft / the craft

Hobby, , skill, education, endeavor, design, building, and/or art of participation, promotion, or activity

CRC

cyclic redundancy check : code used in a to detect an unintentional alteration of transmitted by comparing a computed check of the received data with the check that was received in the transmission; see also

critical frequency

• Highest magnitude of , above which a tends to penetrate the , and below which it is largely back to Earth, related to the by f_c = MUFcosθ_i, in which θ_i is the incidence angle of the wave striking the ionosphere; see also
• See

cross-band / crossband

• Communication method in which a radio receives a signal on one (or ) and simultaneously retransmits the signal on a different band (or frequency), similar to the action performed by a ; see also
• Type of (often called a cross-band ) that can be configured to receive a signal on one and simultaneously retransmit the signal on a different band

cross-modulation / cross modulation

Undesirable from the of one strong signal being superimposed onto ( with) other signals being received, often resulting in hearing an unintended station in the background of the sound from the intended station

crosstalk / cross-talk

Typically undesirable presence of a signal in a circuit or medium, due to unintentional between the and the signal source; see also

CRT

crystal

• See
• See
• Short for
  I actually heard the game on the crystal last night

crystal-controlled transmitter / crystal controlled transmitter

Once popular type of whose is stabilized by the electrical characteristics of a

crystal ladder filter / crystal filter / crystal lattice filter Electronic that uses for its , resulting in narrow and steep ; see also

crystal ladder filter diagram

crystal oscillator / crystal resonator Electronic circuit that uses the mechanical vibrations of a to create an electrical signal with a very precise ; see also Note: many conventional oscillator circuits use quartz crystals as their resonators, so the terms quartz crystal and crystal oscillator are often interchangeable

crystal oscillators

crystal oscillator symbol

equivalent circuit, showing R1 = motional resistance C1 = motional capacitance L1 = motional inductance C0 = shunt capacitance

crystal radio that uses a or as a and is completely by that arrive at its ; see also

crystal radio set

CSCE Certificate of Successful Completion of Examination : document that certifies the named person as having successfully passed a radio examination; see also

CSQ

CTCSS

continuous tone-coded squelch system : circuitry that adds a (formerly and sub-channel) tone to the signal prior to and subsequent transmission, to be received by a or other that requires the tone, so that it will accept the signal and all others; see also and
Note: CTCSS is also known by some proprietary names, such as
• Channel Guard by General Electric
• Private Line ('PL tone') by Motorola
• Quiet Channel by RCA
• Quiet Talk ('QT') by Kenwood
• CallGuard or ToneGuard by Johnson Corp.
• ToneLock by Zetron
• C. Tone by Icom

cubical quad antenna

See

current

Quantity of electrical flow in a circuit, expressed in (symbol A); see also

current balun Type of inserted as a (also called choke balun) to reduce or control undesirable between a and a ; so-called because it attempts to balance the output currents (make them equal and opposite) regardless of the load impedances

curtain antenna

See and

cutoff frequency (also known as the corner frequency and less often as the critical frequency) at which energy through a system or circuit begins to be from its maximum by 3 (output is -3 dB), or half the strength, of the input signal; see also below which a is unable to penetrate a layer of the by at an incidence angle required for transmission between two given points; see also and

cutoff frequency for a filter response

cut out / cutting out

Slang for intermittent or signal continuity during transmission
I could hear most of what you said, but you were cutting out

CVE

Contact Volunteer Examiner : in charge of other VEs in a particular ; the main contact between the and the group of local examiners

CW

• continuous wave : primary for International transmission, in which a steady (continuous) signal is essentially switched off and on; see also
• clockwise : positive angular direction when measuring the of an or a space object (such as a or ); see also

cycle

• See
• Slang for reset, reorder, or restart a piece of equipment
  I needed to cycle the on my
• Slang for complete operation
  The runners had to go through a cycle before they were ready for lunch

DAB

digital audio broadcasting : standard for digital using between 174 to 240 MHz and 1452 to 1492 MHz, adopted primarily by countries in Europe and Asia Pacific; see also

dark side of the moon

CB slang for a location (also called black hole) that is within the of a or other signal source
I'm moving into the dark side of the moon, so my signal will start degrading quickly

data

• Short for (also known as data emission)
  Technicians are permitted to operate both data and on a portion of the
• Any piece of information considered, collected, conveyed, or transferred

data emission

See

data packet

Digitally formatted unit of information (more formally known as a network packet) created by one and transmitted to one or more destination stations; see also

dB

DB-9 / DB9

See

dBc

Ratio of the amplitude of a signal with respect to the power amplitude of the signal, and expressed in ; see also

dBd

of an with respect to that of a antenna, expressed in , and is calculated to be approximately 2.15 dB greater than the gain of an ; see also

dBi

of an with respect to that of an , a hypothetical point source of , and expressed in ; see also

dBm

Ratio of the amplitude with respect to a reference power amplitude in milliwatts, and expressed in ; see also

DBR

dual-band radio : infrequently used abbreviation for a that can transmit on two different , typically the and bands

dBu

amplitude with respect to that of a reference RMS voltage, expressed in ; see also

dBµ / dBµV/m

strength relative to one microvolt per meter, expressed in ; see also

DC

• direct current : unidirectional flow of electric charge () in a circuit; see also

DC resistance

See

DCS

digital-coded squelch : circuitry that adds a digitally encoded to the signal prior to and subsequent transmission, to be received by a or other that requires the tone, so that it will accept the signal and all others; see also and

DC to daylight

Slang phrase meaning all possible frequencies
My can handle DC to daylight

DDC

• direct digital conversion : another name for
• digital down-conversion : process of converting an existing digital signal to that of a lower frequency by for circuitry simplifiction, similar to analog , but with a digital signal; see also

DDRR antenna directional discontinuity ring radiator or directly driven ring radiator : shortened , whose vertical has been formed into a nearly circular (not be confused with a ), and can consist of multiple concentric rings (also once nicknamed the hula-hoop antenna and halo antenna)

DDRR antenna

DDS / DDFS

DE

this is or from; see also
KR5LYS DE KNØJI (KR5LYS, this is KNØJI)

DE-9 / DE9 Model name for a once-common serial port , often mistakenly called DB-9 (and also properly called D-sub or D-subminiature); see also and

DE-9 connectors

de-emphasis / deemphasis

See

dead air / dead-air

Period of silence during a transmission by a (such as or ) that sends a signal, or moment between transmissions of a mode (such as ) that does not; see also

dead carrier

Slang for transmission of an un- signal (also called an open carrier, although an open carrier is often thought to be accidental while a dead carrier is typically a deliberate transmission, such as for testing, and deadkey by operators), which is simply a sine wave of a particular frequency, similar to
If you give me a dead carrier, I can give you a more accurate signal report

dead key / deadkey

CB slang for

dead zone

See

decibel

Ten times the base-10 logarithm of a value, which value is typically a ratio of two other values; 10log₁₀(P_out/P_in), for example; see also

decimation

Process of reducing the effective sample rate of a signal by removing samples; for example, a digital signal by three, then decimate it by four, to adjust its sampling rate by a factor of 3/4; see also

decimator

Device or circuit that uses an to perform the function of ; that is, reduces the sampling rate of a signal; see also

delta loop antenna / delta-loop antenna Variation of the , but with three sides per , each side (leg) being 1/3- long for a symmetrical delta loop

delta loop antenna

delta loop antenna diagram

delta match / delta matching system / delta matching network technique that matches a higher-impedance with a lower-impedance by connecting the to the in two places spaced a fraction of the intended each side of the element center

delta match

delta match diagram

demodulation / demodulate Process of extracting the original information signal, such as your , from within a signal (using a for an signal, for example); see also

demodulation steps of an AM signal

depletion region / depletion layer Insulating section of a doped , in which the primary charge carriers have been repelled by an , leaving only the ionized donor and acceptor impurities, which is achieved by , a , for example; see also

depletion region during reverse-bias

depletion-mode FET

that exhibits a flow between and drain when no is applied; see also

desensitization / desensing / desense / de-sense

Undesirable effect by an signal of a that is close to your expected (receive) frequency and strong enough to overload your circuitry, often because the transmitting source is too close to your receiver (you and your spouse are unable hear each other, even though you're in the same house), or is transmitting with too much , or the of your receiver is set too wide, overcoming your receiver's ability to reject the signal, resulting in and reduced receiver , as well as poor
Note: desensitization is very similar to , except that desensing usually results in a severe reduction in receiver sensitivity, whereas fundamental overload many times results in the receiver shutting down its ability to function at all

destinate / destinated

CB slang for having arrived at a particular location
I've destinated, so to you

detector

circuit (often called a , even though many mixers are not detectors) that recovers () information contained in a ; see also

detune / de-tune

In most senses of the word, opposite of , or action of deviating from a tuned state, also known as a
Your just detuned my

deviation In , maximum difference between the and the frequency; the amplitude of the modulating signal determines the amount of deviation, whose increase results in the FM signal occupying more ; see also

deviation and bandwidth © HamRadioSchool.com

deviation ratio

In , ratio of the maximum from the frequency to the highest signal frequency

DF / DF-ing / DFing

dielectric

Non-conducting (electrically ) material that separates the two conductors of a ; see also

differential-mode current / differential-mode signal

Electrical behavior in a two-conductor or other , such that the in one conductor is perfectly equal and opposite that of the other conductor, resulting in a complete lack of energy produced by the currents; see also

digipeater

Short for digital repeater (sometimes called packet repeater), dedicated to receiving, storing, then re-transmitting digital ; see also

digisonde

Digital version of an to analyze the

digital communication

Communication by transmission and reception of digitized information, called when using as the medium and formatted in an ; see also

digital mode

See

digital decimator

See

digital migration radio

See

digital mobile radio

Open standard for two digital voice signals on a 12.5 kHz , originally used by Professional Mobile Radio, but widely adopted by many manufacturers for , , and applications; see also (also much less well-known as digital migration radio)

digital multimeter Instrument that combines the functions of a to measure electric , an to measure electric , and an to measure , using a digital readout; see also and

digital multimeter

digital radio

Communication by transmission and reception of digitized information by using an ; see also

digital radio mode

Any of several digital communication , such as , , , , , and , for transmitting and receiving digitized information over

digital signal processing

Numerical manipulation of a signal to prepare it for transmission or to the from it; see also

digital signal processor

Specialized that from a signal by converting the signal from to digital and using methods; specifically, automatic of ; see also

digital synthesizer / digital synthesis

See

diode Electronic component (often employed as a ) that allows to flow in only one direction through it (the ordinary type also known as a silicon diode and junction diode), and whose two are called the and the , the cathode end often identified with a painted stripe Some diode types See also

silicon diode

silicon diode symbol

DIP

diplexer Device that allows a single dual-band to operate on two different that support different , or two transceivers of different bands to operate on a single dual-band antenna, or two transceivers of different bands to operate two different antennas using the same (not to be confused with splitter or combiner, both of which normally function on the same band or set of frequencies, or ); see also

mis-labeled diplexer

dip meter Instrument (also called grid dip meter and grid dip oscillator) that measures the of an circuit such as an or by means of tuning a signal generator across the target , indicating the "dip" on the frequency at which maximum power is being absorbed by the circuit; see also

dip meter

dipole Type of that consists of two, usually bilaterally symmetrical, conductive , of which the is perhaps the simplest and most widely used radio antenna, and another common type being the dipole; see also

stick trapped dipole

dipole configurations

dipole center insulator

See

direct digital synthesizer / direct digital frequency synthesizer

Electronic circuit or device used for an arbitrary (method known as direct digital synthesis) from a single, fixed- reference clock, and whose lookup tables contain amplitude values that represent an output waveform, such as a sine wave; see also

directed net

that is under the direction of a , meaning that all communication during the net is directed to and regulated by Net Control unless otherwise requested; see also

direct FSK

Type of in which the digital signal is applied to the for a (typically ) signal; see also and

directional antenna Type of that radiates greater in one direction than in others, or has greater from one direction over others (); see also

directional antenna

directional coupler 4-port waveguide junction device that samples signals at for measuring such as , , and other properties; see also

directional coupler

directionality

Slang for (or layman version of) , as it relates to an

directional wattmeter

See

direction-finding

Activity of searching for a radio signal (also called amateur radio direction-finding or DF-ing) by determining the direction of the signal and locating its source, often used in and to locate sources of , , or ; see also

directivity

Quality of an that describes its transmitting , receiving , and of converting into radiated power in a particular direction compared with the same in other directions; see also

director element

Shortest of a or other , and one that adds to the signal originating from the ; see also

direct radio

See

direct sampling

Method of that involves placing an as close as possible to the incoming signal, reducing or eliminating the need for signal , essentially replacing the circuitry, the term direct indicating an attempt to digitize the incoming signal directly (without modification) before presenting the signal for further processing (, , , etc.); see also

direct-sequence spread-spectrum / direct sequence spread spectrum

Technique of communication that uses a high-speed binary bit stream to shift the of the transmitted signal ; see also

disaster

Situation (often widespread), occurrence, or risk that poses a threat to health, life, property, or environment, and one for which the likelihood of outside assistance (police, fire, , etc.) is low or unknown; see also and

disaster kit / disaster-kit

See

discharge unit

See

discone antenna Type of (version of biconical antenna) that consists of a disc on top and downwardly open cone underneath, both made from sheet metal or sets of rods, but separated from each other by an ; see also

discone antenna of rods

discone antenna of sheet metal

discriminator / discriminate

Circuit used in many for () FM signals by converting signals to signals; see also

dish antenna

See

dissipator / dissipater

See

distortion

Undesirable modification of an or signal, which can result in ; see also

distribution panel / distribution board

See

dither

Small amount of added to the input signal to allow more precise representation of the signal over time; see also

ditty bopper / ditty-bopper / dittybopper

Older slang for military operator, and often one assigned specifically to intercept () encoded messages

diversity reception / diversity operation / diversity combining

See

DIY

do-it-yourself : term (also known as homebrew) that refers to building your own radio gear, especially ; see also and

D layer / D-layer

Lowest (closest to the surface of the earth) section of the , and one (more properly called D region) that absorbs signals of lower than about 7.5 MHz, resulting in difficult daytime long-distance communication on the , , , and ; see also

DMM

DMR

DNR

• digital noise reduction : process or circuit designed to improve a signal by and other undesrirable signals, using software or circuitry (or both) to perform the filtering function(s); see also
• dynamic noise reduction : process or circuit designed to improve an signal by the reduction or removal of background from the signal without the signal having previously been digitally encoded; see also

dogbone insulator / dog bone insulator / dog-bone insulator Non-conductive component that physically connects two or more items that should not be connected electrically, such as , , and structural braces, typically part of an system; see also

dogbone insulators

Doppler antenna array

Mobile variation of , primarily used for ; see also

Doppler shift

Observed change in signal due to relative motion between a and the observer; see also

double

• Unintentional or deliberate of one radio with another, by transmitting at the same simultaneously, usually resulting in both parties sounding mostly unintelligible (note that this term applies more to transmissions on and than to transmissions on bands, in which case the result is usually more of a )
  I believe there was a double with your transmission
• Action of transmitting at the same time as another on the same
  You just doubled with somebody

double-bazooka antenna / double bazooka antenna Type of single- (often simply bazooka antenna) in which the are symmetrically installed as a and the ends of the cables shorted; see also Note: one type uses one element as a single radiator, often in a

double-bazooka antenna

double extended Zepp antenna

See

double half-square antenna / double half square antenna configured as a (often called bobtail curtain) consisting of three quarter- vertical sections connected by one wavelength of horizontal wire (technically, three in- top-fed vertical ) and fed from its upper center or from one of its corners, resulting in a low, bidirectional perpendicular to the horizontal wire Note: some feel that the bobtail curtain is distinguished from the double half-square because the bobtail is fed from the middle vertical section, where the double half-square is fed from the upper corner

double half-square antenna diagram

double-pole, double-throw

See

double-pole, single-throw

See

double-sideband / double sideband Form of in which both are present, but the signal has been suppressed, also known as DSB-SC (double-sideband, suppressed-carrier); see also

double-sideband without carrier

compare with full AM

doublet antenna Center-fed of two quarter-wave horizontal that attach to the through a vertical Note: the is an adaptation of the doublet Classification of , whose are a pair of conductors that form an circuit, of which the is an example

doublet antenna diagram

double-Zepp antenna / double Zepp antenna Center-fed of two half-wave horizontal that attach to the through a quarter-wave vertical often constructed from , making the appearance of two back-to-back

double-Zepp antenna diagram

down-conversion / down conversion / downconversion

• Process of modifying a signal by changing it to a lower , allowing for convenient signal manipulation by circuitry, one step in the process, and integral to
• Process of modifying a signal by changing it to a lower frequency , thereby extending the spectrum available to a

down-converter / down converter / downconverter

Device or circuit that performs the function by changing the of an operating signal to one of a lower frequency, often part of a ; see also

down in the mud

See

downlink / down link / down-link

See

DPDT

DPSK

differential phase-shift keying : low-rate transmission that uses to shift the of an signal to convey the information; see also

DPST

DR

dear : beloved or good, often used as a salutation or greeting, or to describe somebody who is beloved, as in dear friend; see also

D region / D-region

See

drift

See

drip loop Extra length of cable in an or extra length of wire in an electrical installation, to redirect rain and other moisture away from a structure entry point Note: a drip loop can serve as a , but they perform two different functions

drip loop

drive

• Quantity of applied to the input of an , and known as overdrive if the quantity exceeds the amplifier's specification or capability
  Your amp's drive is currently at 20 watts
• Quantity of signal strength (typically , also known as minimum drive, or ) applied to a circuit sufficient to enable its primary function, such as , , or
  The drive required for your array is 80 watts

driven element

Sometimes called the active element, the conductor in a or other that is electrically connected to the or by the ; see also

DRM

Digital Radio Mondiale : set of digital technologies designed to work on the currently used for broadcasting, particularly the bands, making more use of the bands (mondiale is Latin for worldwide); see also and the main

drop out / drop off / dropping out / dropoff / dropout

Slang for abrupt termination of or signal transmission
I could hear most of what you said, but you dropped out near the end

drop-out delay / dropout delay / drop out delay

See

dropout timer

See

DSB-SC / DSBSC

DSP

DSSS

D-STAR

Digital Smart Technologies for Amateur Radio : digital and specification made for ; see also

DTMF dual-tone multi-frequency : telecommunication signaling technology (known as Touch-Tone in push-button telephones, and known as MF4 in the UK) using two combined sine waves ("low" tone and "high" tone) for each signal, to send control commands to a destination device, such as an node or a ; see also

Low ↓      High → 1209 Hz 1336 Hz 1477 Hz 1633 Hz 697 Hz 1 2 3 A 770 Hz 4 5 6 B 852 Hz 7 8 9 C 941 Hz * 0 # D DTMF frequency assignments

DTMF keypad

dual-band / dual band / dualband

See

dual in-line package Type of through-hole electronic component package for made with two parallel rows of connecting pins on opposite sides of the package; see also

DIP IC example

dual-watch / dual watch / dualwatch

feature that allows the listener to two different simultaneously

DUC

digital up-conversion : process of converting an existing digital signal to that of a higher frequency by for circuitry simplifiction, similar to analog , but with a digital signal; see also

duck

Slang or short for

ducting

See

dummy antenna

• Circuit applied in place of an to simulate its while testing a with an instrument such as a signal generator, to prevent inaccurate receiver circuirty alignment
• See

dummy load Device (sometimes called a dummy antenna) usually made of a non- and a heat sink, used in place of an to simulate an electric and prevent the radiation of signals when testing a ; see also

dummy load

duplex

In communication, operation of transmitting and receiving on different , such as in normal operations; see also

duplexer

• Device that uses a to isolate the and on a while permitting them to share a common ; see also
• Mis-labeled

dusk

Any of the three moments in time when the center of the Sun goes 6°, 12°, and 18° below the horizon following sunset; see also and

duty cycle / duty factor Ratio of the amount of time a periodic event is active (the on time) to the entire period (total on plus off time), often expressed as a percentage; see also

duty cycle

DX

distant or long distance : typically refers to a or located outside one's own country, and usually overseas, to Americans also refers to any station outside the continental US and Canada (in many American circles DX can refer to a station located in Hawaii or Alaska, yet not Canada or Mexico); see also and

DXCC

DX Century Club : award given to a who makes verifiable with 100 different countries; see also and

DXCC Entity / DXCC Zone / DXCC Country / DXCC List / DXCC Prefix

Location of an officially recognized by the with whom another station in a different entity can make a verifiable for and other radio purposes; see also

DXer / DX-er / DX'er

Slang for a radio (also called a DX chaser) who makes with distant radio (), on a regular basis as a hobby

DXing / DX-ing / DX'ing

Hobby of making with distant radio , particularly those located outside one's own country, also known as chasing DX; see also and

DXpedition / DX-pedition / DX'pedition

• Journey (expedition) by one or more radio to a distant, exotic, remote, difficult, or sparsely inhabited location or , often to set up a at a location where few hams normally reside nearby, in an effort to provide the opportunity for hams world-wide to make with a station in that location; see also
• See (special )

DX QSL manager

See

DX window

specified by a voluntary that is reserved for , and should not be used for between within the forty-eight United States

dynamic range

Ratio of the largest to smallest signals by a , and expressed in ; see also

early-out / early

Slang for announcement or request to check into a then leave prior to its conclusion, to alert the that the operator should not be called upon at a later time in the net; similarly spoken as in-and-out, out after roll (for a ), and short-time
Could you please give me an early-out tonight?
This is KNØJI and I'm in-and-out
This is KNØJI, out after roll (for roll-call nets)
This is KNØJI for short-time

earphones

See

earth connection

See

earth ground

Type of (also called earth connection and ground connection) identified by direct connection with the Earth; see also

earth-moon-earth

See

earth station

radio located on, or within 50 km of, the earth's surface and intended for communication with or other earth stations by means of one or more objects in space

EAS

EchoLink

Software-based system that radio around the world through your cell phone or other computing device using Voice over IP; see also and the official EchoLink website

ECOMM / Ecomm

EDC

everyday carry or every-day carry: one or more useful items (such as a phone, knife, or as it relates to , an ) carried consistently (often daily) by a person for utility, preparedness, and self-sufficiency purposes; see also

Edison effect

See

effective aperture / effective area

See

effective isotropic radiated power

Quantity of (also called equivalent isotropic radiated power) required to transmit a signal in all directions equally, from a theoretical spherically radiating (total power radiated from an isotropic source, as observed by a distant , making EIRP = ERP × 1.64, or EIRP is ERP + 2.15 dB); see also

effective radiated power

Realized amount of output radiating from the in a particular direction when compared with a reference antenna, especially a ; see also and

efficiency

Measure of a system output compared with its input, expressed as a ratio or percentage; as it relates to electric , it is defined as the useful power output divided by the total power input to a circuit or device, and often represented by the symbol η; for example, the efficiency of an power can be calculated by dividing the RF output power by the input power; see also and

EFHW

EFRW

egg insulator Non-conductive component that physically connects two or more items that should not be connected electrically, such as , , and structural braces, but provides for the connection in such a way that, should the insulator become damaged or be destroyed, the conductors will maintain their structural connection after their electrical separation is compromised, typically part of an system; see also

egg insulator

EH antenna

Specially designed that produces electric (E) waves and magnetic (H) waves that travel both and perpendicular to each other, to improve , thereby allowing for a smaller construction while maintaining the performance of conventional antennas; see also a technical description of the EH antenna

EHAAT

See

EHF

extremely high frequency : overall range of 30 GHz to 300 GHz; see also and the RF spectrum

EIRP

or

E layer / E-layer

Section of the (also known as the Heaviside layer and more properly called E region) responsible for that can reach up to approximately 1200 miles along the earth's surface normally covered in one ; see also

electret

Stable material that produces an electrostatic field originating from a permanently embedded charge (unlike a magnet, which produces a magnetic field); see also

electret microphone

Type of electrostatic -based (sometimes called an electret condenser microphone as a result), that eliminates the need for a polarizing by using permanently charged material; see also

electrical grid

Interconnected network (often shortened the grid) of that deliver electrical (sometimes called line voltage) from multiple to the many consumers that require it, and is the primary source of commercially available to homes, businesses, and facilities; see also

electrical service Distribution box and meter (often shortened service), typically located outside a building, for providing from the power company or to the building or facility; see also

electrical service drop

electrical service panel / electrical panel Known by many names (breaker box, breaker panel, distribution panel, distribution board, service panel, fuse box), the location at which the is distributed from the through to the various circuits of a building; see also

electrical service panel

electric field

Physical influence originating from an electrically charged particle, surface, or changing / moving , and one that can exert a force on another electrically charged object; see also

electric potential

See

electric shock / electrical shock

Physiological reaction or injury caused by flowing through body tissue, and can range in severity from a barely perceptible tingling sensation to electrocution; see also

electrode

Wire or other electrical conductor that provides a path to an electrical device or circuit, some conductors labeled according to path function, such as those for a (emitter, base, collector, , drain, , etc.) or ( and ); see also

electrolytic capacitor Type of polarized that is often used in circuits to the due to its ability to present a high for a given volume; see also

electrolytic capacitors

capacitor symbols

electromagnetic compatibility

Ability of an eletrical device or system to function acceptably in its electromagnetic environment, by limiting unintentional generation, , and reception of ; see also

electromagnetic interference

Undesirable disturbance of normal operation by the introduction of electromagnetic or ; see also and

electromagnetic radiation Form of energy consisting of electromagnetic waves, which are synchronized of and fields that at the speed of light and oscillate perpendicular to each other; see also

electromagnetic spectrum Range of all possible of ; see also

electromotive force

Electrical force (pressure, or ) that moves through a circuit, expressed in volts; see also

electron

Sub-atomic particle that possesses an elementary negative charge, and whose flow (movement) forms the definition of electrical ; see also

electronic keyer

See

electron tube

Older term for

electrostatic discharge

Sudden flow of electricity (of which is an extreme example) between two or more electrically charged objects when the difference in charge overcomes the ability to prevent (by distance or type) the transfer of energy; see also

element

• Either or conductor section whose length, shape, and size help determine the of the antenna
• Numerical designation for a set of examination questions that are presented to a candidate, such that currently Element 2 represents the , Element 3 represents the license class, and Element 4 represents the license class; see also and FCC rules for exam element credit
• Dot or dash in
• See

elephant

Slang for a , especially a , that seems to receive farther than it could transmit a signal (think big ears, little mouth); see also

elevation

• Angle of incline from horizontal, with respect to level
• Appearance of something as it is viewed from its side; for example, an elevation of an (often called its or takeoff angle) is its transmission strength pattern as seen looking at it from the side of the antenna; see also

ELF

extremely low frequency : overall range of 3 Hz to 30 Hz, which is lower than that considered part of the regular radio frequency range, and has been used to communicate with submarines due to its ability to penetrate deep seawater; see also and the RF spectrum

elliptic filter / elliptical filter Signal that produces a response with a very narrow (very sharp transition), coupled with equal ripples in the and sides; see also

elliptic filter response

elliptical polarization of in which the travel path of the electric field describes an ellipse in relation to the direction of travel; see also

blue = electric field path orange = side view of the electric field purple = resulting apparent ellipse

elmer

Slang for a (usually experienced) mentor or tutor who offers personal guidance, technical knowledge, assistance, and encouragement to radio , especially newcomers and potential hams; see also and the article that coined the term

ELT

emergency locator transmitter : device () that transmits a signal to indicate location or position during a time of or distress; see also

EMC

EMCOMM / EMCOM / EmComm

EME

earth-moon-earth : communication technique that relies on the of signals from an to an earth-based by reflecting the signal off the surface of the moon, often referred to as moonbounce; see also and

emergency

Unexpected of unusual or serious concern, alarm, or danger, often associated with a situation that has compromised, or poses an immediate risk to health, life, safety, property, or environment; see also
• steps to take during an actual emergency

Emergency Alert System

Dual-purpose national (established through the ) public warning system that 1) directs a variety of , cable, and broadcasters to provide the President of the United States the ability to address the nation within ten minutes and 2) coordinates with FEMA and NOAA's NWS to warn the public on a more local level about , such as imminent severe weather or other environmental conditions that affect public well-being; see also and the main

emergency communication

Communication (abbreviated EMCOMM) of any type and by any means during a , a drill, or an actual ; see also and

emergency traffic

See

Emergency War Powers

See

EMF

• electromagnetic field : physical influence, consisting of an and a , emanating from an electrically charged object; see also

EMI

emission

Transmitted signal (one that is emitted from a location, especially a ); see also and

emission designator / emission designation

Internationally accepted (-organized) 7-character abbreviation that describes an signal and classification; see also
Some common designators (without the 4-character prefixes)
• A1A :
• A3E : ordinary , used by and
• F8E : multi-carrier , used by on
• F3E : ordinary , used by on (typically)
• J3E : voice, used by

emission mode designator

See

emission privilege

Permission an operator holding an appropriate to use one or more particular ; see also

emission type

See

EMP

electromagnetic pulse : short burst of (usually high-energy) that can be disruptive or damaging to electronic equipment, primarily due to the high amount of it can in them; see also and Noji's EMP page

emphasis

Modification of the amplitude-vs.- characteristics of a signal to reduce the adverse effects of , using a pre-emphasis network to increase (boost) the amplitude of higher frequencies with respect to that of lower frequencies, and a de-emphasis network to decrease the amplitude of higher audio frequencies with respect to that of lower frequencies; see also

EMS

emergency medical services : trained personnel who provide urgent pre-hospital treatment, stabilzation, and care for an individual who has incurred a serious injury or illness; see also

encryption / encrypted

Encoding of a , transmission, or its information, such that it can only be read or understood by a receiver that is capable of decoding, or authorized to decode, the message; see also

end-fed / endfed Type of design whose connects to one end of a , as in those of a , or even a configuration; see also

end-fed antenna

end-fed Zepp antenna / endfed Zepp antenna

See

entity

See

entrance panel / entrance ground

See

EOC

emergency operations center : central command and control facility responsible for implementing emergency preparedness and emergency management functions at an upper-management level during an or other ; see also

E-plane / E plane Flat geometric surface defined by the electric wave component of an in a particular direction, also known as the vertical plane or elevation plane of a , or the horizontal plane or plane of a horizontally polarized antenna; see also

E and H planes for a vertical antenna

E and H planes for a Yagi antenna

equivalent isotropic radiated power / equivalent isotropically radiated power

See

equivalent radiated power

See

ERC

Emergency Response Communications : department of the LDS Church responsible for communication and its preparation and training; see also ERC and Lindon Bishops' Storehouse

E region / E-region

See

ERP

E_S / Es

Abbreviation for

ES

and or also (not technically a ); see also
ES

ESD

E-skip / E skip

See

ESR

equivalent series resistance : total effect of an electrical component or circuit (device) at a given , as though the resistance is in series with the device; see also

evaluation

See

even-order harmonics

See

event

See

EWE antenna Receiving variation on the and , consisting of two short vertical sections connected by a short horizontal wire, and fed typically from one of its lower corners through an and terminated in a Note: the author of this antenna notes in his article that the name EWE is not an acronym, but merely spelled to help the reader understand the antenna name pronunciation

EWE antenna diagram

exam session / examination session

Formal and official arrangement to assess a candidate for knowledge and qualification through an examination

excessive drive

Signal strength (typically or , known as ) applied to a circuit greater than the amount the circuit can tolerate, possibly resulting in (on ), malfunction, overload, or even permanent damage

excessive deviation

See

exchange

Predetermined trade of information transmitted and received during a to verify the for , and usually includes your , but often includes a sequence number, general location indicator, or

excitation

• Quantity of (also known as excitation voltage) required to activate a circuit to perform its primary function
  For example, many require a minimum excitation voltage to "turn on" the amplifier and start the action
• Quantity of required to activate a of a generator; see also

exciter

• Once-popular device or circuit of a -type that combines an with the to create its output signal
• Device or circuit that the of a or

exposure evaluation

See

extended double-Zepp antenna Center-fed of two 5/8-wave horizontal that attach to the through a quarter-wave vertical often constructed from , making it a little longer than the

Extra

See

extraordinary wave

One of two types of (also known as an X-wave) that results from the interaction with the and the one that is polarized by the influence of earth's magnetic field; see also and

eyeball QSO

Slang for an in-person (sometimes face-to-face) meeting between without the use of
We had an eyeball QSO the other day

EZNEC / EZ-NEC

Variation of the design modeling and simulation software; see also and the main

F10.7 Index

See

F1 connector / F2 connector Faston 1 / Faston 2 : model name for a common gendered electrical (also called blade and spade and tab) terminal often used with and other low- household (, etc.) or portable (scooter, , etc.) ; see also and

F2 connectors

F1 layer / F1-layer

See

F2F

F2 layer / F2-layer

See

F8E

See

FAA

Federal Aviation Administration : agency of the federal government responsible for regulating every aspect of civil aviation, including the construction and operation of airports and air traffic management; see also

factory reset

See

fall arrest / fall arrester / fall arrestor Type of climbing harness designed to safely stop a climber who is already in process of falling, and one of the major forms of fall protection; see also

fall arrest climbing harness

fall protection

See

fan dipole antenna Type of (also called parallel fan dipole), in which multiple parallel radiating join at a common point on each side, or in which the radiating elements spread out radially from the common points, like with a antenna

fan dipole antenna

Faraday, Michael English scientist whose contributions to the fields of electromagnetism and electrochemistry led to the discovery of , which forms the basis of ; see also and

Michael Faraday

Faraday rotation

Interaction (also called Faraday effect) between light (or other , such as ) and a , resulting in a rotation of the plane of the magnetic field in the direction of ; see also

far-field / far field

View of a for an or other object capable of , as observed from a sufficiently distant point, to examine the overall behavior of the field; see also
• (for a more technical description)

fast Fourier transform

Digital process applied to in order to recover the information, essentially converting the digital signals from the time domain to the domain; see also

fast-scan television

See

FB

fine business : OK or alright; see also

FCC

Federal Communications Commission : agency of the US government that regulates communication in general; see also

F connector Common 75 Ω non-weatherproof, gendered (also called F-type connector) often used on for and other applications; see also and

F connectors

FDM

FDMA

FEC

feed

See

feeder

Short (primarily British) term for

feed line / feedline

Set of electrical wires or other conductors (sometimes feed for short) that transfers signals between a and an or other component, such as an , a , or a ; see also

feedline coupler / feed line coupler

See

feed point / feedpoint

Point in an system (sometimes antenna feed) where the meets the or other ; see also

feed-through capacitor / feedthrough capacitor

See

ferrite choke / ferrite bead Type of that uses a ferrite ceramic to suppress high in circuits; while ferrite chokes and ferrite beads are usually regarded as the same electrically, ferrite beads often refer to the ferrite ceramic core without the wire winding; see also

snap-on ferrite chokes

built-on ferrite choke

ferrite beads

ferrite-core transformer

See

FET

FFT

F/H / FH

FHSS

Field Day

Annual twenty-four-hour period, usually the last full weekend in June, in which engage in a to collect as many verifiable with other hams as they could , to promote training for rapid deployment of equipment; see also and

field-effect transistor characterized by a high input , using , , and drain (the gate electrode creating an electric field to control the flow through the device), and whose general operating characteristics most resemble that of a ; see also

field-effect transistor

FET symbols

field-programmable gate array Programmable designed to be configured by a customer after being manufactured, to create complex logic functions in a single integrated circuit; see also

FPGA

field strength meter / field-strength meter Electronic device that measures the intensity at a distance from a , once used to determine an antenna's and monitor relative output when making antenna and transmitter adjustments; see also and

field strength meter

filament

Heating element of a

filter Circuit used to improve a signal (by removing from the signal, for example) or process a signal (between the and the in a , for example); see also Some filter types Some application-specific filters

graphs of various filter types

filter choke

See

filtering

• Process of improving a signal by reducing , , and other undesirable effects, or preparing the signal for further processing by other circuit
• Circuit designed to perform the signal improvement process or modification
  The contains some unique filtering

filter skirt

See

final

• Slang for a concluding transmission before leaving the
  I'll be on your final
• Short for , especially the or used for
  After troubleshooting my , I had discovered that its finals were blown

final amplifier

Device or circuit placed in a where the output signal meets the , and can be little more than a in the of an or as large as a separate unit

finite impulse response

Type of whose impulse response is finite, in that it will eventually reach zero, resulting in a filter that is easier to design, and delays all components of the signal by the same amount; see also

FIR

fist

• Older slang for a 's style
  I can tell by his fist that he's new at operating
  It's fun to an with a good fist
• Older slang for a , especially an inexperienced one
  He's a new fist, so you might to start slowly with him

five-and-nine / five-by-nine / five-nine

See

five-by-five

See

five-over-nine

See

fixed station / fixed-station

See

flag antenna

See

flash conversion ADC / flash ADC

Type of that uses a linear ladder and a comparator to measure the input voltage with respect to successive reference voltages; see also

flat braid

See

flat strap

See

flat-topping / flat topping

See

F layer / F-layer

Highest section of the , and the one (more properly called F region) mainly responsible for the longest , which can reach up to approximately 2500 miles along the Earth's surface normally covered in one , and during the day separates into the F1 layer and F2 layer; see also

flip-flop / flip flop / flipflop Digital used to store a bit (binary digit), forming the fundamental building block of digital electronic systems, and can be used to divide a frequency signal by two; see also

SR flip-flop animation

float voltage

at which a is maintained after being fully charged, to compensate for self-discharge, and which can vary significantly between battery types; see also

floating ground

Type of that is not electrically connected with the Earth, such that its electric can differ from that of ; see also

FM

• Short for

FME for mobile equipment : model name for a somewhat uncommon 50 Ω (primarily ) used for in applications; see also and

FME connectors

FM radio

• Nickname (also called FM broadcast and FM band) for the portion of the that is dedicated to , which in the US spans 87.8 MHz to 108.0 MHz, using 0.2 MHz spacing of odd tenths of one MHz; see also
• Nickname for an

FM slope detector

See

foldback / fold back

Device (, , or of a ) output circuit that attempts to limit the amount of being drawn by the , to help protect the device from overload; see also

folded dipole antenna Type of half-wave typically constructed from one wavelength of wire forming a very thin loop, whose is approximately 300 Ω; see also

folded dipole antenna

folded dipole antenna diagram

footprint

Geometric area covered or occupied by a physical device; see also
The footprint of my is very small compared with that of my

formal traffic message

See

forty six / forty-six

for Greetings on your birthday and best wishes for many more to come; see also

forward error correction

Technique for controlling transmission errors during unreliable or communication; see also and

forward power

Measure of signal strength (also called incident power) as it reaches a or change (discontinuity), and expressed in watts; used to calculate and

four-square antenna / four square antenna

See

fox / hound

Special operating (more formally called DXpedition Mode), in which a (the fox, often an ) attempts to attract the attention of another station (the hound) to facilitate a rapid exchange of communication and confirmation; see also the FT8 DXpedition Mode User Guide

fox hunting / fox-hunting / foxhunting / fox hunt / foxhunt Also called transmitter hunting, T-hunting, and rabbit hunting, activity in which participants attempt to locate a hidden by means of , using a ; see also

FPGA

FPIS

F region / F-region

See

frequency

Number of wave cycles that occur in one second, expressed in Hertz (symbol Hz), and is approximately f ≈ 300 ÷ λ, in which λ is the in meters and f is the frequency in MHz; see also the RF spectrum chart for frequency designations and

frequency allocation

Assignment, coordination, and regulation (also called spectrum allocation and spectrum management) of segments within the for use by various , such as , , and communication; see also

frequency band

See

frequency coordination

Assignment, , and agreement on local and use, as part of an organized , to minimize between ; see also

frequency coordinator

Volunteer person or group that is selected by local to recommend transmit / receive and other parameters for and stations; see also and

frequency counter Instrument that measures the precise of an input signal; see also and

frequency counter

frequency deviation

See

frequency discriminator

See

frequency division multiple access

Method of accessing a particular channel of a transmission system that requires high-performance for reliable communication; see also

frequency-division multiplexing / frequency division multiplexing

Communication technique by which a is subdivided into a series of non-overlapping sub-bands, each of which is used to carry a separate (either or digital) signal, thereby giving the appearance of transmitting signals of multiple frequencies simultaneously on a single ; see also

frequency drift

Undesirable and arbitrary change in , often due to temperature variation and component aging, and expressed in Hz/s; see also

frequency-hopping spread-spectrum / frequency hopping spread spectrum

Technique of communication in which the of the transmitted signal is changed very rapidly according to a particular sequence that's also used by the receiving station; see also

frequency modulation Method of combining an information signal (your , , , etc.) with an signal of constant amplitude, so that the of the output signal varies with the information signal; see also and

AM and FM waveforms compared

frequency multiplier

See

frequency privilege

Permission an operator holding an appropriate to use one or more particular ; see also

frequency response

Quantitative measure (often simply response) of the magnitude and phase of device or circuit output across a range, as a function of input frequency; see also

frequency synthesis

Creation of multiple (synthesized frequencies) or from a single reference (often a -based) frequency signal, rather than from a continuously- circuit or multiple , the two primary methods being synthesis and ; see also

Fresnel zone Roughly ellipsoidal (football-shaped) volume of space between a and a defined by potential object (obstruction) locations lying off the , resulting in possible constructive (aided by ) or destructive ( by ) patterns, as in , often resulting in and other irritating sound effects; see also

front end / front-end

Generic term for all the circuitry between the and the ; typically, all the components in the receiver that process the original incoming signal before it is converted to a lower ; see also

front end filter / front-end filter

Portion of a that provides a , to reduce strong, out-of-band signals and

front end overload / front-end overload

See

front-to-back ratio Ratio of the forward to the rearward gain of a , typically measured in ; see also

FRS

Family Radio Service : set of by the under for , -free, and short-distance use, primarily in ; see also and a chart of assigned FRS/GMRS frequencies [PDF]

FSK frequency-shift keying : low-rate transmission in which the signal is transmitted through changes in a wave , of which and are the two major types, and with and being most applicable forms to (relatively) modern radio; see also

FSK441

frequency-shift keying, 441 baud : type of transmission () at 441 , designed to support communication using events; see also

FSTV

FT4

Franke-Taylor, 4-FSK : type of transmission (specifically, ) designed to support very communication by decoding signals many below the (low conditions) using , is less sensitive than or , but transmitting at 6-second intervals, which is 2.5 times faster than in completion; see also
• FT4 description

FT8

Franke-Taylor, 8-FSK : type of transmission (specifically, ) designed to support very communication by decoding signals many below the (low conditions) using , is less sensitive than or , but transmitting at 15-second intervals, which is four times faster in completion; see also

F-type / F type

See

full break-in / full break in

operating (also called ) that allows a listening to between the very of a transmitting station's individual dots and dashes, making the communication resemble operation; likewise, allows the transmitting station to receive a transmission between sending code and characters; see also

full-duplex / full duplex

Communication method that allows sending and receiving transmissions simultaneously; see also

full gallon

See

full-quieting

Signal that's clean enough for the receiving to all perceptible , , and other , such that the transmitting station is understood clearly; see

full-wave bridge

that is constructed from a network of to perform the function; see also and

full-wave loop antenna Also called skyloop, skywire loop, loop skywire, and horizontal loop, adaptation of the constructed with wires whose combined length totals greater than one full , and with all points of the wires installed at the same height off the ground

full-wave loop antenna diagram

full-wave rectifier , such as a , that converts the entire input , instead of only a portion of it (see ), into ; see also

full-wave rectifier circuit

fundamental Lowest signal of a periodic ; see also Older slang for parent

fundamental and its overtones

fundamental overload

Undesirable effect (also called receiver overload, front-end overload, and RF overload) by an signal that is strong enough to overcome the circuitry (overcome the receiver's ability to reject it) by entering the receiver through its components rather than through the , possibly because the transmitting source is too close to the receiver or is transmitting with too much , resulting in of the signal, or even shutting down
Note: fundamental overload is very similar to , except that desensing usually results in a severe reduction in receiver , whereas fundamental overload often results in the receiver shutting down its ability to function at all

fuse Automatically operated electrical device, typically placed in series with a conductor that supplies to a circuit, that interrupts the flow of through the circuit when the current exceeds a specified rating for a particular amount of time, to protect the powered equipment in case of overload, and is typically not re-usable after being blown; see also and

glass tube fuses top = 'blown' bottom = 'good'

fuse symbols

fuse box

See

Fusion

See

G5

Most severe level of measurable (labeled extreme), in terms; see also

G5RV Shortened version of the and adaptation of the , , fed with and a through a length of open-wire (such as ), serving as one of its ; see also

G5RV antenna

G5RV antenna diagram

G5RV, Junior / G5RV Junior / G5RV, jr / G5RV jr

Version of the physically shortened for space restrictions, and typically limited to and higher

gain

• In general, ratio of the output to input signal (can be , , or ) strength change by a circuit or device, often measured in or similar unitless designation; see also
• See
• Quantified ability of a to produce an output signal ( or ) that is proportional to a weaker input signal; see also
• Quantified ability of an to increase signal strength () at its output, compared with that of its input, often measured in (or , depending on amplifier type); see also

gain antenna

Slang or nickname for an that exhibits a greater than 0 (typically much greater than zero, such as 6 dBd or 9 dBd), without regard to

gain compression Ratio of the amount of nonlinear ( due to ) with respect to its ideal linear gain, expressed in , and often associated with that have a wide (not to be confused with dynamic range compression, a desirable audio process); see also

graph showing gain compression

gallon

• Slang for 1000 watts (or often full gallon when referring to 1500 watts)
• Slang for 1 kW when referring to or 1.5 kW when referring to or other
My 's running a full gallon

gamma match / gamma matching system / gamma matching network technique that matches an to an by connecting the feedline to the antenna at both the center of the and at a fraction of the intended to one side of the element center, the series capacitance intended to cancel the of the matching network

gamma match

gamma match diagram

gassy tube

into which some air molecules have penetrated, possibly changing some of the tube characteristics; see also

gate

• Controlling electrode of a or
• See

gateway

radio that is used to connect other ham stations to the internet

gauge

See

Gaussian minimum-shift keying

Form of transmission in which the data stream is shaped with a Gaussian filter prior to modulation; see also

gear

• Slang or short for any kind of radio equipment
  I plan to some more gear at the next
• Slang or short for any kind of equipment
  Don't forget your snow gear on the way out

geezer

Older slang for a (typically) older male who insists (in writing or vocally, especially ) that the way he does things is the only right way to do them; see also
Note: being a geezer has ilttle to do with age, gender, or hobby involvement, but is more defined by attitude

General

Current mid-level radio whose privileges cover most of all , and that certifies the as one having a much greater understanding of regulations, operating practices, and electronics than that of a class licensee; see also

general coverage / general-coverage

Feature attributed to a that can accept and signals outside the , specifically (typically) 100 kHz to 30 MHz, often for

geomagnetic index / geomagnetic indices Semi-logarithmic quantification of disturbances in Earth's magnetic field, denoted primarily by the K-index (0 through 9), which can vary throughout the day (an indicator of the short-term stability of the earth's magnetic field), and often accompanied by the A-index (0 through 400), which is a daily average (an indicator of the long-term stability of the earth's magnetc field); because measurements of these values could vary between earthly locations, the planetary (meaning global) KP-index and AP-index are often provided instead; disturbances such as can affect radio communication greatly, with generally the higher the index the more HF communication is degraded; see also

solar activity report showing the current planetary (globally averaged) indices KP and AP in the upper portion of the left column

geomagnetic storm

Temporary disturbance in Earth's , resulting in both degraded high-latitude and , which can reflect signals, and rated according to this chart:

Scale	Severity		Per year
G1	Minor	5	155
G2	Moderate	6	55
G3	Strong	7	18
G4	Severe	8	9
G5	Extreme	9	< 1

see also

geometrical horizon / geometric horizon

See

geostationary Appears to stay in one position, or does not appear to move, relative to the earth, referring to an object that is orbiting in a circle directly above the equator, applicable to and orbits; see also Note: a geostationary orbit is a special case of the geosynchronous orbit, in that not only is the orbiting object synchronized with the earth's rotation, but it's also orbiting 1) in a circle and 2) directly over the equator, making it appear motionless

geostationary illustration

get kit / get-kit

See

getter

Reactive material deposited in a to absorb or chemically combine with air molecules that penetrate the evacuated enclosure, to maintain the tube's vacuum; see also and

GFCI

GFI

ghosting

See

giga

Prefix, or units modifier, to indicate × 1,000,000,000 or × 10⁹, and is abbreviated G

gin pole Rigid rod, or supported pole with a pulley system, to safely lift or hoist an , section, or other equipment into a position where it can be secured to a structure or another section below it; see also

gin pole

gin pole use diagram

glass-mount / glass mount / glassmount Type of made from (typically) two metal pieces that adhere to opposite sides of a glass window or other non-conductive surface, and connect to each other by , with one of the pieces forming the base of an antenna, typically for and applications

glass-mount antenna

glowbug Slang for a or made with ; see also and

glowbug

glow-in-the-dark / glow in the dark

Slang for the description of a -type

GMRS

General Mobile Radio Service : set of by the under for , , and short-distance use, primarily in ; see also and a chart of assigned FRS/GMRS frequencies [PDF]

GMSK

GMT

See

go ahead

begin speaking now; see also

go-box / go box

• See
• See

go-kit / go kit / gokit Type of survival equipment package (also known as go-bag, 72-hour kit, jump-kit, ready-kit, bug-out bag, grab-n-go kit, get-kit, disaster-kit, bail-out bag, go box, and battle box, with the longer-term [as in several days] type more appropriately referred to as a survival kit) that can be quickly picked up and carried by an individual during a moment of or other crisis, and usable for at least 72 hours; see also

go-kit

goniometer Device that measures the angle between two distant objects with respect to a stationary position (similar to a protractor, but typically with moving parts) to aid in by use of , for example; see also Device or software feature that displays the asymmetrical phase differences (asymmetric goniometer) in a stereo audio signal pair; see also

goniometer

GOTA Get on the Air : general invitation to radio to become active in the ; see also Get-On-The-Air : particular set up in conjunction with to allow inactive or non- individuals to participate in making , subject to ARRL rules [PDF]

GPS

global positioning system : government-sponsored and space-based navigation system that provides location and time information anywhere on or near the earth within of four or more GPS satellites, regardless of weather conditions; see also

grab-n-go / grab and go / grab-and-go / grab & go

See

grace period

Time interval between expiration and license cancellation, during which a can renew the license without being required to re-take the exam and can retain his/her , but is not permitted to transmit using the until the license is renewed

grant

Issue, bestowal, or award of a or certificate, typically the result of proficiency demonstration or examination, such as a license grant

Gray code

Digital code (binary numeral system) in which the character preceding or following a particular character differs by only one bit, which facilitates error detection; see also

gray-line / gray line / grayline / grey-line

Type of by enhanced along the between daylight and darkness, which occurs around sunrise and sunset () when D-layer absorption (which absorbs HF signals of lower than 15 MHz) is weak, while and propagation remain strong; see also and

green horn / green-horn / greenhorn

See

green stamp Slang for US dollar (USD) bill

green stamp

grid

• Portion of a that controls the flow of electrons internally from the to the (plate), or in other words, the flow of internally from the anode to the cathode, and usually includes a control grid, screen grid, and suppressor grid; see also
• Slang or short for
• Short for

grid current

See

grid dip meter / grid-dip meter / grid-dip-meter / grid dip oscillator

See

grid locator

Also called Maidenhead Locator and locator, world-wide system of letter-number designators assigned to a specific geographical area known as a , outlined by latitude and longitude boundaries; see also and a

grid power

See

grid square

Letter-number designator assigned to a specific geographical area measuring 2.5 minutes latitude by 5 minutes longitude, by the system; see also

ground Reference point in a circuit by which are measured, and often include , and ; common return path for electric in a circuit; see also and Physical connection to earth , often called earth ground and station ground (not to be confused with , which ensures two points have the same potential, which can be earth ground potential)

ground symbols

ground braid / grounding braid / flat braid Cable typically made of braided tinned copper or braided copper for , which ensures two points (such as equipment) being connected have the same electric , which ideally is potential

ground braid

ground connection

See

ground electrode / grounding electrode

See

ground-fault circuit interrupter / ground fault circuit interrupter Type of fast-acting (formerly GFI, ground-fault interrupter, and outside the US often known as RCD, residual-current device) designed to shut off electric in a circuit when it detects that more is flowing through one conductor than through its return path conductor, indicating a possible imbalance, which typically occurs if part of the current is flowing through an unintended path, such as water or human tissue; see also and

American GFCI outlet

grounded-grid amplifier / grounded grid amplifier

Type of , with the (and sometimes the screen grid) of the tube connected to , which configuration provides a low input and simplifies design, while nearly eliminating the potential for self-, but suffers from relatively low ; see also

ground loop

Undesirable condition in which two points in a circuit that are supposed to be at the same (usually ) are actually at different potentials; see also

ground panel Also called entrance panel or entrance ground or single-point ground panel, electrically conductive surface or bar () used as a common connection point for multiple devices and cables, typically to with an outdoor connection, such as a

ground panel

ground plane Type of named for the electrically conductive surface or network (of rods, wires, cones, screens, etc.) attached to the antenna to compensate for lack of direct connection to Electrically conductive surface (, car body, refrigerator, etc.) or network (of rods, wires, cones, screens, etc.) that serves as the ground part of a (typically ) ; see also Electrically conductive area of a printed circuit board or independent circuit that serves as the signal reference for the circuit

ground plane antenna

ground rod / grounding rod Metallic electrode (also called ground electrode) installed in direct contact by relatively large surface-area with the (dirt), to provide a path to earth ground or electrical reference; see also

copper-clad ground rod

ground strap / grounding strap / copper strap Flat ribbon conductor made of copper (often called flat strap or copper strap) for equipment in your to minimize losses in your grounding system

flat copper strap

ground wave / ground-wave Type of (also called surface wave) that uses the area between the surface of the earth and the for signal transmission, and can often follow the curvature of the earth for some distance, thereby extending beyond the ; see also

grounding

• System of interconnected wires, , , and cabling that provides a stable electrical reference to (preferably earth ground); see also
• Practice of providing or ensuring a connection to potential (also called earthing in the UK)

G-scale

See

guard

Slang for aircraft (121.5 MHz AM for civilian and 243.0 MHz AM for military) reserved for distress communication; see also

guide wire / guide-wire / guidewire

Misspelling or mis-pronunciation of

gummers

Slang or short for

Gunn diode Electronic (also known as a transferred electron device) that is uniquely distinguished from other kinds of because it presents a negative with a positive applied ; used primarily in high- applications such as speed guns, , and microwave ovens; see also

Gunn diodes

Gunn diode symbol

Gunn diode oscillator

Circuit that is dependent on the negative properties of a to produce ; see also

guy-wire / guy wire / guywire / guy-line Rope, cord, or other (typically flexible) cable used to support a or of a , to keep the structure in a particular position or prevent it from falling or from excessive motion, due to or other movement; see also and

guy-wires supporting an antenna mast

HAARP

High-frequency Active Auroral Research Program : program established by the University of Alaska Fairbanks to analyze the and investigate the development of ionospheric enhancement technology for communication and surveillance by using a high-power , , and , among other instruments; see also

HAAT

height above average terrain : difference (also known as EHAAT, or effective height above average terrain) in altitude of an site and the altitude of the average surrounding landscape of interest, often used by engineers, but also used by those installing an to help determine repeater range; see also

HAGL

half-duplex / half duplex

Communication method that allows sending and receiving transmissions one direction at a time, so that the listening is unable to transmit until after the end of the currently transmitting signal; see also

half-power bandwidth / half power bandwidth / halfpower bandwidth

See

half-power beamwidth

See

half-square antenna / half square antenna configured as a consisting of two quarter- vertical sections (that hang down like a curtain) connected by a half-wavelength of horizontal wire and fed (typically) from one of its upper corners, resulting in a low, bidirectional perpendicular to the horizontal wire

half-square antenna diagram

half-wave dipole / halfwave dipole Type of that consists of two identical, and usually bilaterally symmetrical, conductive that together are measured to be one-half- of the intended times the of the element material, and is the antenna that provides the reference for measurements

half-wave dipole antenna

half-wave dipole antenna diagram

half-wave rectifier

Circuit or device that converts () exactly half of the input , instead of the entire signal (see ), into ; see also

halo antenna

See

ham Slang for hobby, practice, or equipment associated with , originally a taunt expressed by professional operators (some assert the unsubstantiated claim that HAM might be an acronym); see also for an explanation on the possible origin of the word for yet another explanation I enjoy ham Richard owns a lot of ham Slang for hobbyist or practitioner My father was also a ham

ham band

See

HamCation

Specific and unusually large held annually in Orlando, Florida; see also and the main

ham cave / hamcave

See

HamCon / Ham-Con

See

hamexpo

See

hamfest

Informal social gathering or convention (sometimes hamvention and hamexpo and Ham-Con) between people who are interested in radio, and can include exhibits, forums, and a ; see also and

ham-in-a-can / ham in a can Slang for a , including , , and , along with other support , that is built into a carrying case, such as an ammunition ("ammo") can, similar to a Slang for equipment that's been installed on, or attached to, a computer dedicated as a digital for communication using , , or other

ham-in-a-can

ham net / hamnet

See

ham police

See

ham radio

Nickname for

ham radio band

See

ham radio operator

See

ham shack / hamshack

See

hamspeak / ham speak

Language, terminology, and slang used among radio , hobbyists, and enthusiasts

hamvention

See

handheld transceiver (also known as a handy-talkie or HT or handy-scratchy or simply handy) that is small enough to carry around in your hand; see also and

handheld transceiver

handle

• Older slang for first name
• CB slang for nickname

handy-talkie / handy-scratchy

See

hang time / hangtime

See

hard line / hardline / hard-line Type of that consists of a solid outer conductor instead of braid, resulting in very low , typically used in applications; see also

Heliax hardline

harmful interference

Serious degredation, obstruction, repeated interruption (also called willful and malicious if it is deliberate), or excessive that prevents proper operation at any time, especially during an or other critical moment (said to be harmful because a person's life could depend on your ability to communicate)

harmonic Nonzero whole number (natural number or 1, 2, 3, etc.) multiple of a , such that the fundamental frequency is the first harmonic, twice the fundamental frequency is the second harmonic, etc., and such that the odd-numbered multiples are identified collectively as odd-order harmonics and the even-numbered multiples as even-order harmonics ( do not include the fundamental frequency); see also Older slang for child, particularly that of a

Hartley oscillator circuit that generates a using supplied through a , and is one of (at least) three primary oscillator circuits used in equipment, commonly in a circuit; see also

circuit employing a Hartley oscillator

hash

Short for and older slang for

HASL

hat trick / hat-trick

See

health and welfare traffic / health-and-welfare traffic

See

headphones / head phones Pair of small speakers (sometimes earphones and cans) worn on or over the ears by a , can also be a single speaker instead of a pair; see also

headphones

headset / head set Combination of and used as a unit by a for two-way communication; see also

headset

heater

Nickname for

Heaviside layer

See

Heliax Brand name (often Andrew Heliax or Andrew cable) of a very low-, rugged, and relatively expensive , often characterized by a corrugated outer and a low-density foam (often abbreviated LDF in product names) or air

helical resonator Type of used typically in a to isolate or protect a particular signal from by other RF signals close in to that used by nearby repeaters or other (such as and telephone); see also and

VHF helical resonator

Hepburn map

Graphical image to aid in predicting the probability of for

Hertz

See

heterodyne / heterodyning (combining) of two signals to shift them into a range that is easier to process, for purposes of and ; see also Undesirable audible rise and/or fall whine created by the of two mismatched signals that are attempting to combine into an

audible heterodyning example click to listen

HF

high frequency : overall range of 3 MHz to 30 MHz (although most also include the band when considering the HF spectrum); see also and the HF frequency designation in the RF spectrum

HF scatter

of signals as they are scattered into the through several different paths, often resulting in a wavering or sound

HH

high-cut filter / high cut / highcut / hi-cut / hicut

See

high-pass filter Circuit or device that out most or all signals with lower than a particular cut-off frequency, thereby allowing signals of all higher frequencies to pass through the device (also called low-cut filter because it "cuts off" the lower frequencies), useful for preventing from entering sensitive circuits and low-frequency signals from interfering with the intended signal, such as with the case of ; see also Note: many are outfitted with a low-cut filter setting, to allow filtering out ambient ; while most high-pass filters are designed for frequencies, most low-cut filters are designed for audio frequencies

high-pass filter

high-speed multimedia radio

high-speed network (mesh) over using commercial off-the-shelf hardware such as a WiFi router or equipment, for use in Amateur Radio Emergency Data Network (AREDN); see also
• main Broadband-Hamnet (BBHN) / HSMM-Mesh website
• main AREDN (successor to BBHN) website

HI HI / HIHI

ha ha : laughter; see also

Hilbert transform filter / Hilbert-transform filter

Type of often used to generate a signal; see also

hit the repeater / hitting the repeater

Slang for access the repeater or communicate with the repeater, in an effort to make use of a 's repeat and other functions (such as or )
I can you, but you're not hitting the repeater

HOA

homeowner association : corporation established by a real estate developer to market, manage, and sell homes and lots in a residential subdivision, which management can include enforcement of applicable that limit the installation of radio equipment; see also

hold the repeater / holding the repeater

Slang for keep the repeater open or maintain repeater access, in an effort to maintain continuous use of a 's repeat and other functions (such as or ); see also
I can you, but you're not holding the repeater

hole Lack of an electron at a position where one could exist in an atom or atomic lattice of a doped material; see also

hole left after an electron leaves an atom

hole-mount / hole mount

See

holiday-style / holiday style

Slang for a relatively relaxed operating plan (typically in reference to a or station), in which operation might be seccondary to the intended journey, or that making contacts is not the station's first priority (the station will operate as time permits, in between activities, for example); often synonymous with

homebrew / home-brew / home brew

Slang for home-made; see also and and the DIY page

hop

Travel path of a from the to the , then down to a ( refers to the mode, while hop refers to the path of travel); see also and

horizon Perceived boundary between earth and sky from a given height visual horizon / visible horizon : also known as skyline, apparent line or circle that separates the earth from the sky, whose distance is approximately 8 percent greater than the geometrical horizon because of downward bending caused by atmospheric density variations; see also radio horizon : distance over which two can communicate by direct path (also known as line-of-sight propagation when applied to signals of frequencies higher than 30 MHz), approximately 15 percent greater than the geometrical horizon because of downward bending caused by atmospheric density variations; see also and geometrical horizon / true horizon : calculated boundary between a spherical body (such as a star, planet, or moon, but in most applications, a spherical earth) and its sky, assuming ideal (no atmosphere) conditions; see also

diagram showing geometrical horizon H to observer O of height h

diagram showing radio horizon compared with visual horizon

horizontal channel amplifier

See

horizontal loop / horizontal sky loop

See

horizontal orientation

Alignment of an 's primary physical , parallel to the level surface of the earth, with the intent of creating and a signal

horizontal polarization Alignment of a signal's parallel to the level surface of the earth (actually, perpendicular to the vector force of Earth's gravity), and a signal with such an alignment is said to be horizontally polarized; see also

hot

• Slang for wire or other conductor in a (particularly ) electrical system that has electric relative to ; see also
  The is inserted into the hot wire side of your
• Slang for over- (as in a ) that results in
  Your is running hot
• Slang for excessive amount of signal flowing in the cabinetry or housing; see also
  My housing is way too hot (notice the reference here is unrelated to temperature)

hot-carrier diode / hot carrier diode

See

hot mic

• Slang for that is switched on
  I accidentally some rather personal comments while my was hot
• Slang for over- that results in
  Your is hot
• Slang for a that is accidentally left switched on, such that the is transmitting without the operator realizing that it is; see also

hound

See

house current / house power

See

household power

General-purpose household electrical that is supplied to a home, business, or facility; see also
Note: people in the UK tend to agree on the term mains power when referring to household electrical power, while we in the US are in general disagreement on what to call it, due primarily to the conflict between common modern usage and precise descriptive language, and so have come to use a variety of terms such as house current, AC power, commercial power, utility power, city power, shore power, wall power, outlet power, line voltage, etc., for convenient reference

HPBW

HPF

H-plane / H plane Flat geometric surface defined by the magnetic wave component of an in a particular direction, also known as the vertical plane or elevation plane of a horizontally , or the horizontal plane or plane of a polarized antenna; see also

E and H planes for a vertical antenna

E and H planes for a Yagi antenna

HPSDR

high-performance software-defined radio : open-source (GNU type) hardware and software project defining next-generation by a more modular approach (using a common bus); see also and the main

HSMM

HT

hula-hoop antenna

See

hum

• Unwanted and often constant low- sound, characteristic of an unintended or within a circuit
• See

Hz

Symbol for Hertz, which is the basic unit of , defined as one cycle per second, equivalent to s⁻¹; see also

iambic keyer / iambic paddle Dual-paddle telegraph that requires a (typically sideways) squeezing action to produce tones, unlike a ; see also

iambic keyer

IARP

International Amateur Radio Permit : permit that allows a licensed of participating (North, South, Central American, plus Caribbean) countries to operate in any other participating country without an additional or permit; see also and
Note: operating an amateur in an IARP country using class or higher privileges ("Class 1") requires demonstration of proficiency

IARU

International Amateur Radio Union : international collection of national organizations that provides a forum to address common concerns and represents issues to the ; see also and IARU / ITU region map

IBOC

in-band on-channel : method of transmitting an and signal simultaneously on the same by multiplexing the analog signal with a digital ; see also

IC

ID

• identification : in most cases, a
  The 's ID is K7UVA
• State or send a
  You need to ID every ten minutes and at the end of your communication

IF

IGBT

IIR

image

• Communication (such as and ) used for transmitting pictures over , often for reporting severe weather information, location announcements, and individual identification; see also
• See

image rejection

Ability for a to reject unwanted signals that result from ; see also

image response

Undesirable signal generated when a a with a received signal to produce an signal; in other words, the unwanted signal is a 'mirror image' of the receive signal in response to the mixing function; see also and

imbalance current

See

IMD

IMF

IMI

impedance

Quantity of opposition to flow in a circuit, expressed in ohms (symbol Ω) and defined as Z = R + jX, in which Z is the impedance, R is the real () , j is the imaginary unit, and X is the ; see also and and

impedance matching / impedance-matching

Practice of designing or adjusting the of a circuit or signal to maximize the amount of transferred to its , or minimize the amount of returned from its load, by presenting a complex conjugate of the load impedance, the failure to properly match a load to its source called an impedance mis-match; see also

impedance-matching device

Circuit or device that provides a resonable electrical between two circuits of possibly differing , such devices as a , or network of or electrical components; see also

IMRR

image response rejection ratio : ratio of signal strength produced by the received signal with respect to that produced by the , expressed in ; see also

in-and-out

See

incident

Situation, occurrence, or risk that poses a threat to health, life, property, or environment, and one that might require the services of an Incident Management Team or Incident Response Team; see also

Incident Commander

Highest-level leader in the National Incident Management System during a particular , and the person in charge of managing and coordinating all resources in conjunction with the incident; see also and

incident power

See

inductance

Property of a conductor that defines its ability to store electrical energy in a magnetic field to resist changes in the through it, expressed in henries (symbol H), and whose magnetic field can induce (create) a voltage in itself and one or more nearby conductors; see also

inductance index

Specification of , dependent upon its material , dimensions, and shape, expressed in per square turn

inductive coupling

Effect of two or more circuits not connected to each other being close enough that an through one can result in an AC across the others through ; see also

inductive reactance

Imaginary quantity of opposition to flow in a circuit () due to , that varies with and is expressed in ohms (symbol Ω) and defined as = ωL, in which L is the inductance and ω is the frequency in radians (ω = 2πf, in which f is the frequency in Hz); see also

inductive time constant

See

inductor Electrical component that opposes changes in electric passing through it and stores energy in a magnetic field; these include air- , iron-core , and ; see also and

assorted inductors

inductor symbols A = air-core B = ferrite choke C = iron-core

inductor core Metallic, powdered-metallic, or other material (the movable type sometimes called a slug in a ) inserted or built into an to set or vary the of the component, of which soft iron, ferrite, air, and some special alloys are among the most common, and include solenoidal core (cylindrically shaped) and toroidal core (donut-shaped) as common types; see also Note: brass can be used as core or slug material to actually decrease the inductance

assorted inductor cores

inductor showing its slug core

inductor saturation

See

inductor self-resonance

See

inductor tap

See

infinite impulse response

Type of whose impulse response can be infinite, in that it might never reach zero, resulting in a filter that is generally easier to implement for a given set of requirements; see also

informal traffic

See

in-phase / in phase / inphase

• Description of two signals whose values or values reach their peak levels at the same time; see also
• See

input-offset voltage / input offset voltage

Differential input of an required to bring its open-loop output voltage to zero; see also

input frequency

Value of a 's at which it receives incoming signals to eventually re-transmit them on its ; see also

inrush current

Initial surge of electrical drawn by a circuit or device immediately upon applying electrical to the circuit, often much greater than its steady-state current; see also

insertion loss

Signal introduced by the addition of an electrical component, such as a , , meter, , or extension, and typically measured in ; see also

insulated-gate bipolar transistor High- used as an electronic that combines the switching speed of a BJT with the efficiency of a MOSFET, and used in switched-mode power supplies for high-power applications such as trains, UPS, arc-welding machines, air conditioners, and electric cars; see also

IGBT symbol and photo

insulator

Material that does not conduct electric under working , such as plastics and glass; see also

integrated circuit

Device that combines several and other components into a single package (chip) or collection of packages (chipset), which can be digital (such as a ) or (such as a voltage ); see also

intercept point

See

interference

Anything that discrupts or modifies a signal; interruption or excessive in a radio transmission; see also and
Your radio is putting out a lot of interference

interlaced scanning

Technique used to double the perceived frame rate of a video display without consuming extra by displaying all the odd-numbered lines, followed by all the even-numbered lines; see also

intermediate frequency

to which a signal is shifted as an intermediate step during transmission or reception to improve ; see also

intermodulation distortion

Undesirable signal (often abbreviated intermod and IMD) generated by the of two or more signals with different , arising from system nonlinearities, and resulting in and (IMI) with an excessively large (not to be confused with ); see also
Note: the term IMD typically refers to the undesirable mixing of signals involving , while PIM (passive intermodulation) refers to the undesirable mixing involving , such as antennas, cables, and even nearby corroded fencing, giving rise to the slang term rusty bolt effect

intermodulation interference

Undesirable effect (often abbreviated IMI) of (IMD)

internal resistance

Equivalent in series with an ideal source, collectively representing an electrical circuit or device, often a or , that aids analysis of device health or integrity; see also

International Morse code

See

international reply coupon

Post office coupon that at one time could be exchanged for postage stamps representing the minimum return postage for a card or letter to the country that issued the coupon, but is no longer issued by US post offices; see also

International Telecommunication Union

United Nations agency responsible for issues that concern information and communication technologies, and coordinates the shared global use of the spectrum; see also and the main

interoperability

Idea, theory, and/or program of coordination, collaboration, and communication between a variety of entities, such as government agencies, public safety, and computer nodes in an effort to share relevant data and promote information exchange toward a common goal, such as public welfare, aid, and relief (and typically does not involve but can); see also

interplanetary magnetic field Portion of the solar magnetic field that is carried by the among the planets of the solar system (interplanetary space); see also

IMF interaction

interpolation

Process of mathematically increasing the sample rate of a signal (upsampling); for example, interpolate a digital signal by three, then it by four, to adjust its sampling rate by a factor of 3/4; see also

in the mud

See

intrinsic Meaning natural state, as it applies to , material or portion (region) of material that has not been doped, but exists in its extremely pure form, opposite of extrinsic; see also

PIN diode diagram showing intrinsic region i

inversion

Atmospheric condition (also called temperature inversion), in which the temperature of air rises with an increase in altitude, a departure from its normal behavior, resulting in trapped pollution, freezing rain (in colder climates), and due to the increase in refractive index of the atmosphere near the temperature differences; see also

inverted-L antenna / inverted L antenna / inverted ell antenna Type of , part of whose section is bent over and parallel to the ground; see also

inverted-L antenna diagram

inverted-V antenna / inverted V antenna / inverted vee antenna Type of whose is the highest part of the structure, with sides slanted down toward the ground; see also

inverted-V antenna diagram

inverter Electrical device that converts a power source to voltage, typically 120 ; see also See

inverter

inverting

Type of non--specific that re-transmits a received signal at the same passband offset from the end of its as that of the received signal, but on the opposite end of the passband (roughly mirrored image of the received signal); see also and
Example: suppose that a linear transponder's receive passband is 432.000 MHz to 432.100 MHz, and its transmit passband is 146.000 MHz to 146.100 MHz. If it receives an signal on 432.008 MHz (therefore using a passband offset of 432.008 MHz − 432.000 MHz = 0.008 MHz), the transponder will re-transmit on (146.100 MHz − 0.008 MHz = ) 146.092 MHz, and in

ionizing radiation

, made of both energetic subatomic particles and high- (typically > 3 PHz), that possesses enough energy to ionize (free electrons from) the atoms and molecules of living tissue, which in turn can cause genetic damage; see also and

ionoscatter

See

ionosonde

Device that uses to scan the and report the to calculate optimum operating frequencies suitable for communication; see also

ionosphere Region of the upper atmosphere that is ionized by solar radiation and influences to distant places on earth as a result, reaching its maximum height where the sun is overhead; see also

ionospheric layers

ionospheric scatter

Form of (sometimes called ionoscatter) in which are by the of the , allowing for communication between 25 MHz and 100 MHz as a result of irregularities or discontinuities in that atmospheric region

IOTA

Islands on the Air : list of islands or island groups designated and labeled by the Radio Society of Great Britain (RSGB, the British counterpart of the ) for and other radio-related purposes; see also

IP3

See

I/Q data / IQ / I and Q signal in-phase / quadrature : components of a signal that reflect changes in the amplitude and of a sine wave, used for or in analysis; see also

I/Q components of a modulated signal

IRC

IRLP

Internet Radio Linking Project : system that radio around the world using Voice over IP by keying specific signals; see also and the main

iron-core transformer whose wires or other conductors are wound around an iron, silicon steel, or ferrite center to help concentrate and confine the in an effort to maximize its ; see also

iron-core transformer

iron-core transformer symbol

ISB

independent sideband : form of in which two different signals are , the of one and the of the other, then transmitted together without the signal, and once formed the basis for stereo; see also

I signal / I data

See

ISM

industrial, scientific, and medical : collection of -free that are internationally for use primarily by industrial applications, yet secondarily overlap several parts of the ; see also

isolator

See

IsoPole antenna Brand name (often Spectral IsoPole) for a once-popular center-fed (isolated, center-fed dipole) that uses a pair of collinear, downward-opening decoupling metal cones, and was known for a very low-angle of radiation; see also the main and an [PDF]

IsoPole antenna

isotropic antenna

Theoretical used as a reference for antenna measurements, and has no gain in any direction; see also

isotropic radiator

Hypothetical point source of , used as a measurement reference for and other ; see also

ISS International Space Station : habitable facility in permanent , used for testing and experimentation of a huge variety of cases under (seeming) gravity-free, out-of-atmosphere, and other physical conditions unique to those in earth orbit; see also main ISS website

ITU

ITU phonetic alphabet

See

ITU Region Any one of 3 major geographic world areas, as defined and named numerically by the ; see also and ITU Region map

ITU Zone Any one of 75 geographic areas of the world, as defined and named numerically by the ; see also ITU Zone map

J3E

See

jam / jamming

Deliberate (malicious) of a radio signal by the use of or other signals, in an illegal attempt to disrupt communication; see also

J antenna / J-antenna

See

Jones filter

Variable- , used as part of an

JOTA

Jamboree on the Air : annual scouting event that uses radio to connect scouts around the world, usually held on the third full weekend in October; see also
• JOTA on BSA

joule

The basic unit of , represented by the symbol J; see also

J-pole antenna (also J antenna) whose shape roughly resembles the letter J due to its half- and quarter-wavelength stub; see also

2 m copper J-pole antenna

dual-band open-stub J-pole antenna

J-pole designs

JS8 / JS8Call

Jordan Sherrer-designed 8-FSK : type of transmission similar to , but adds keyboard-to-keyboard text messaging; see also the main

JT65 / JT-65

Joe Taylor, 65 tones : type of transmission (specifically, ) designed to support , , and other very communication by decoding signals many below the using ; see also

JT65-HF

Alternative extension to the transmission designed for communication on at very low levels; see also

JT9 / JT-9

Joe Taylor, 9 tones : type of transmission (specifically, ) designed to support very communication by decoding signals many below the using ; see also and

jumper Short length of (often called a pigtail, patch cable, or simply patch) for connecting two pieces of equipment with the same type, different connector types, or different genders of the same connector type, or for extending the length or reach of a cable Removable electrical component used for connecting two or more pins or posts that are installed on a printed circuit board or other surface, to make such a connection available

PL-259 to SMA jumper

electrical jumpers

jump kit / jump-kit / jumpkit

See

jump off

Slang for an intention to leave the current conversation
I need to jump off, so to you

junction diode

See

junction transistor

See

K

for , indicating that any operator may respond

kc

keep-alive / keep alive / keepalive

• Device (typically a backup or large or capacitor bank) that maintains a level of and provides a sufficient amount of to allow critical tasks (time-of-day, odometer, security lockout, etc.) to remain running while the primary becomes temporarily unavailable; see also
• Circuit that detects whether the backup storage device is operating, as a result of the loss of from the primary
• and/or a preionizing radioactive source material that maintains a minimal area of ionized gas (sometimes called glow discharge) near one of the gap electrodes or a within a , allowing for rapid conduction for when the output spikes

Keplerian elements Parameters (occasionally shortened keps) required to identify a specific orbit of a celestial body (such as a ); see also

diagram showing all the Keplerian elements

keps

Slang or short for

kerchunking

Slang for momentarily pressing the button on your or (often activating a ) without identifying yourself, a practice that is generally frowned upon

key Action of Please key your when you're ready to transmit Telegraph key (sometimes keyer) used for communication; see also Action of pressing a telegraph key (also called key press) to produce a signal

straight telegraph key

key click

Undesirable click sound produced in a transmission once a is depressed or released, and the settling time happens to be longer than the rise or fall time of the CW signal, at one time very problematic when attempting to copy a weak signal near a stronger nearby signal

keyer Circuit or device that converts a into a series of consistenly spaced and timed electrical signals that represent dots and dashes, for communication, either a mechanical keyer, which produces the signals by a physical means, or an electronic keyer, which produces them electronically, allowing for programmatic control of spacing and timing parameters; see also Person who communicates by Tom is a keyer Telegraph used for communication; see also

keyer using a keyer

key up / key-up

• Action of pressing a button on your , especially the button, or (originally) engage the telegraph key
  You need to key up to transmit
• Press of the button on your or, (originally) of engaging your telegraph key
  I hear a with every key-up of his

kilo

Prefix, or units modifier, to indicate × 1,000 or × 10³, and is abbreviated k

kilocycle

Outdated term for kilohertz (kHz)

K-index / K index / K_P-index

See

KISS

keep it simple, stupid : once-common communication ; see also

klystron Specialized that uses in high- , , and and and ; see also

klystron

KN

Somewhat outdated for go ahead or , or back to you (at one time, to indicate the is listening for, or returning control to, a specific , but has since largely been replaced simply by )

knife-edge / knife edge / knife-edging / knife edging

Form of diffraction in which a encounters an obstacle with a sharp boundary, such as a mountain range or the edge of a building, creating a new wavefront that seems to bend the original wave around the object and away from the with the signal source; see also

K_P-index

See

ladder line Type of consisting of two wires (often called open-wire line or abbreviated OWL) separated by insulators acting as spacers holding them together / apart every few inches, giving it the appearance of a ladder, and possessing lower signal loss than such as at (window line is a type of ladder line in which the two conductors are separated by bands of molded plastic or similar, also called ribbon line); see also

window lines

lamp Electrical device capable of producing (typically incandescent) light; see also

small lamps

lamp symbol

Land Mobile Radio Service / landmobile

See

L band

Alternate name for the

LC circuit / LC network Circuit (often called a tank circuit because of the resemblance to a tank full of electrons sloshing back and forth between one component and the other) made of and , for use in , , and signals; see also

LC (tank) circuit at resonance

LCD liquid-crystal display : electronic device that displays images using the light-modulating properties of liquid crystals; see also

LCD mounted on a circuit board

LC oscillator

Circuit that includes an and a connected (in a configuration often called a ) to form an , whose is determined by the and in the circuit; see also

LCR meter Test instrument that displays the (symbol L), (symbol C), and (symbol R) of an electronic component or electrical circuit; see also and

LCR meter

LDE

LDF

low-density foam : model name / prefix for a common type of used in cable and other versions of

LED

legal limit

The highest amount of () allowed by the for use, or 1500 watts (1.5 kW); see CFR section 97.313(b)

LEO

• low earth orbit : Earth orbit that is between 99 miles and 1200 miles above the surface of the Earth; see also
• law enforcement officer : policeman, sheriff, deputy, state trooper, etc.

Leyden jar / Leiden jar Crude electrical device once used for temporarily holding a high- (estimated 20 kV to 60 kV) electric charge, and original complete forerunner of the modern , consisting basically of a sheet of foil that lines the inside of a glass jar, connected to a rod or other conductor that protrudes through the lid (and often topped by a to prevent or slow atmospheric charge leakage), plus another sheet of foil that wraps around the outside of the glass jar; see also and Note: the first Leyden jars merely consisted of a glass bottle partially filled with water or alcohol, plus a nail driven through the cork and immersed in the liquid; the experimenter's hand wrapped around the outside of the bottle provided the other capacitor plate conductor, and often gave the person a tremendous electrical shock when contacting the nail with the other hand

Leyden jar

Leyden jar diagram

LF

low frequency : overall range of 30 kHz to 300 kHz; see also and the RF spectrum and

LFA loop-fed array or loop fed array : type of whose is a regtangular , resulting in high , high , and high rejection

LFA Yagi antenna

LFP

See

license / licensing Authorization by the of an to operate a radio within and appropriate for the of privileges to the ; see also and

reference copy of Noji's license [PDF]

license class

See

licensee

Person who holds a valid operating , and the one presumed by the to be the of an station

license trustee

See

lid Insult akin to moron, usually directed at an inconsiderate radio or one who seems to regularly demonstrate sub-human intelligence by ignoring rules, making obscene remarks, or bullying new hams (originally meant inept when directed toward a new ham or raw beginner)

LiFePO4 / LiFePO4 lithium iron phosphate : type of (also called LFP for lithium ferrophosphate) that offers a longer lifetime than do other battery types, is safer, exhibits little or no memory effect, and is known for high energy density compared with that of other batteries, and relative low weight but high cost and high and constant charge / discharge rate compared with that of batteries; see also

LiFePO4 batteries

light-emitting diode that gives off light when it is forward-biased; see also

assorted LEDs

LED symbol

lightning Sudden , normally during an electrical storm, between electrically charged regions of a cloud, between a cloud and another cloud, or between a cloud and the , often referred to as a strike, and is a form of ; see also and Noji's Lightning page

lightning arrester / lightning arrestor / lightning protector Device (also called surge protector and antenna discharge unit) inserted in a to protect conductors and their insulation from the damaging effects of nearby or other large by diverting much of the voltage surge to ; see also (more applicable to amateur equipment) (less applicable to amateur equipment)

lightning arrester

lightning dissipator / lightning dissipater Device that reduces the likelihood of strike to a structure or craft by presenting the potential discharge with multiple sharp, conductive points, thereby preventing the build-up of charge, which normally invites lightning Note: the usage and effectiveness of a lightning dissipator are somewhat controversial

lightning dissipator

lightning protection

Collection of measures and apparatus designed to minimize the harmful effects of or buildup on a structure, people, equipment, and other vulnerable targets by attempting to route much of the damaging energy to and provide a means for an equi-potential between structure, equipment, and internal circuits; see also and

Li-ion lithium-ion : type of that exhibits little or no memory effect and is known for high energy density compared with that of batteries, and relative low weight but high cost and high charge / discharge rate compared with that of batteries; see also

Li-ion batteries

limiter / limiting

See

line

• See
• See
• See
• Any visible or imaginary path defined or identified for purposes, such as or
• Any conductor of electrical energy, such as a wire in a circuit, , , supply line, or line
• Pathway for communication (communication line), such as a telephone landline
  a line to the chief
• Row of characters forming a text

Line A

Imaginary line roughly parallel to, and south of, the US-Canadian border, north of which amateur stations are not permitted to transmit between 420 and 430 MHz; see also
• CFR section 97.3(a)(30) definition of Line A
• map of Line A

linear amplifier (often shortened linear and also called power amplifier) whose output preserves the input , and is usually a ; see also and

linear amplifier

linear power supply Type of that converts electrical to power directly, without pulsing the energy during the conversion process, and is typically much heavier and less efficient than a , but also sometimes less (electrically) and more expensive; see also

linear power supply

simple (unregulated) linear power supply schematic

linear transponder

See

line isolator

See

line noise

See

line-of-sight / line of sight

Type of that occurs between two points in a straight, unobstructed (to radio waves, not to eyesight) path; see also and

line voltage

See and

link

Communication connection, typically by internet, of a much higher , or being directly wired, between two or between one and another, each point connected this way being called a
Your main repeater and ours are linked

link budget

Signal intensity measured at a after it has been generated, , , and (what's left of the transmit at the emd of the entire RF chain); see also

link dipole antenna Type of made from pairs of conductive sections that can be connected ("linked") together a pair at a time, for each supported

LIPD

low interference potential device : classification of a device (whose potential for interference is low) that has been for short-range (low-power) operation, such as Wi-Fi, garage door openers, barcode readers, and , primarily applicable in Australia

lip mount / lip-mount Type of that combines an attachment method with a fixture connection for installation on the edge of a sheet metal body, such as that of a vehicle trunk or metal cabinet or enclosure

NMO lip mount

Li-Po / LiPo / Li-poly / LiPol lithium-polymer, or more correctly, lithium-ion polymer : type of that either contains a polymer electrolyte or is encased in a polymer package, and exhibits little or no memory effect; see also

Li-Po battery

liquid-crystal display / liquid crystal display

See

listening

• Invitation for any other operator to talk with you
  KI7ABC listening
• Announcement that you are simply on a with your radio on, in case somebody needs assistance, but not actively participating in a conversation; see also
  I'll be and listening
• Act of awaiting information on a frequency, or multiple frequencies, in search of communication activity

listen out

Slang for continue listening on this until the end of the conversation
You two continue with the and I'll listen out

LiTZ

litz wire Type of electrical wire made of multiple thin strands of individually insulated (often coated) conductors, constructed to reduce at , and therefore ; see also Note: litz wire is known to work effectively up to 500 kHz, with quickly diminishing effectiveness above 1 MHz, and so have found applications such as in windings around bar , for example

litz wire

LMR-240

Model name for a 50 Ω low- used as a best-suited for and applications; see also the coax chart [PDF]

LMR-400

Model name for a 50 Ω (also available in 75 Ω) very low- used as a well-suited for , , and applications; see also the coax chart [PDF]

LMRS

LNA

L network Circuit made from an and a , one in series with the signal input, and the other in , that serves to an external with that of the signal , and is the equivalent lumped-constant network for a hairpin matching system on a three- ; see also

L network

LO

local oscillator : portion of a circuit, used for converting a signal of one to another; see also

load Circuit that is connected to the output of a circuit, such that typically the source circuit provides electric to the load, and the load consumes the power from the source; see also

application of an electrical load

loaded dipole , each of whose is shortened through some of its length being partially coiled up as a near the element center

loaded dipole diagram

loading

Act of inserting an (called a loading coil) in the radiating portion of an to make it electrically longer, typically to permit operation with a shortened antenna

loading coil used in an , or between an antenna and its to make an electrically short antenna at a specific by canceling the ; see also and

loading coil

lobe Spatial signal represented graphically by a balloon or raindrop shape, which shows the relative field directions and signal strengths logarithmically proportional to the distance from the source, typically an ; see also

antenna pattern lobes

local control

Type of control in which the is physically at the ; see also and

log / logging

• File, submission, or other record (sometimes called logbook or log book) of made between two , and could include , dates, times, , , and other pertinent information
• Action of recording such a contact

logic circuit

• See
• Electronic circuit made from active components used for creating, storing, and manipulating digital logic

logic gate

Fundamental digital circuit (also called logic circuit) that performs a particular , of which the most common include
— inverts the input
— any high input drives the output high
— all inputs must be high to drive the output high
— (inverted OR) any high input drives the output low
— (inverted AND) all inputs must be high to drive the output low
— inputs must be different to drive the output high
— (inverted XOR) inputs must be different to drive the output low
see also

log-periodic antenna Type of narrow-beam that consists of a collection of that are sized and spaced apart according to a somewhat logarithmic scale, and operates over a wide range of (has a wide ); see also

log-periodic antenna

long-delayed echo / long delayed echo / long-delay echo / long delay echo

signal that returns to the transmission point of origin, often after several seconds; see also

long-path / long path / longpath

Method of that uses the path from your to a station along the path in the opposite direction of the great circle arc of the earth, at times supported by all , and most frequently available on the band

Long Tone Zero / Long-tone Zero / Long Interval Tone Zero

Loosely defined alert method within the in which a person in need of help can issue an alert by pressing and holding the Ø (zero) key on a keypad for three or more seconds to send a tone that can potentially a that supports the , or at the very least can alert another who might be the

long wire antenna / long-wire antenna / longwire antenna

See

longwave

range broadly defined as having greater than 1000 meters (frequencies below 300 kHz), which includes the entire and ; see also

lookup table / look-up table

Array of pre-programmed steps in a , that replaces direct computation, to improve generation speed; see also

loop

• See
• See
• See
• Circular, oval, or arc shape, such as a loop of wire

loop antenna

Type of whose and possibly other are formed into a relatively circular, oval, or even arc shape, and includes and , both of which are classed as small transmitting loop antennas; see also

loop skywire

See

LoRa

long range : physical, proprietary technique based on pulses made from a low- and low data stream; see also

LOS

loss

Quantity of signal strength expended, dissipated, or absorbed without contributing to its productive use (wasted), or ratio of the strength of such a signal to that absorbed by a , measured in ; see also

loss resistance

See

LOTW

Logbook of the World : online database implemented by the ARRL to provide a contact verification service for radio toward awards (such as , , and ); see also and

loud and clear

audio is strong and perfectly understandable; see also

loudspeaker / loud speaker

See

low-angle radiation

Primary or average field of an that is radiated at a relatively low predetermined angle, with respect to level ; see also

low band / lowband

Slang for

low-cut filter / low cut / lowcut / lo-cut / locut

See

lower sideband / lower-sideband

• Common operating derived from and is used on the , , and ; see also
• Older slang for younger sibling

lowest usable frequency

below which are completely absorbed by the , making them unusable for transmission between two points; see also

LowFER / LOFER

low-frequency experimental radio
• Experimental, -free communication practiced by hobbyists on below 300 kHz (), and more specifically between 160 kHz and 190 kHz (often called the 1750-meter band) in the US and Canada, where the length is limited to 50 feet and the output is limited to 1 W; see also and and the main
• Slang for a practitioner who experiments with communicating (also called lowfing) on below 300 kHz ()
  My dad was a LowFER until he retired from altogether

low-impedance short circuit

Undesirable or abnormal electrical path made by a connection between two conductive points in an existing circuit by a path or conductor possessing a finite amount of resistance that is small enough to cause the circuit to malfunction; see also

low-noise amplifier

Electronic circuit that increases the intensity of very weak signals, such as those that are received from a and its attached , without compromising the signal's , and typically used in the of a circuit; see also

low-pass filter Circuit or device that out most or all signals with higher than a particular cut-off frequency, thereby allowing signals of all lower frequencies to pass through the device (also called high-cut filter because it "cuts off" the higher frequencies), useful for preventing generated by transceivers from interfering with household or neighboring devices; see also

low-pass filter

LPDA

log-periodic dipole array : most common type of , consisting of a number of , mounted parallel and relatively close to each other

LPF

LPRS

Low Power Radio Service : set of by the under for low-, , and short-distance use, primarily in medical and hearing-impaired applications; see also the main

LRC circuit

See

LRC meter

See

LSB

LTZ

LUF

LW

long wave : range broadly defined as 30 Hz through 300 kHz, which includes the and a portion of the band; see also

M17

Mokotowska 17 : type of open-source, royalty-free, and adaptable digital and created for ; see also and the main

machine

• Slang for
  I heard the Blue Peak machine is down at the moment
• Infrequently used slang for
  Picked up a new machine the other day

magic band

Nickname for the due to its high volatility and unpredictability

mag loop

See

mag-mount / mag mount / magmount / magnetic mount / magnetic-mount Type of made from a permanent magnet that is attached to the base of an antenna, typically for and applications

mag-mount antenna

magnetic core

See

magnetic field

Physical influence originating from a static magnetic source or changing / moving , and one that can exert a force on an electrically charged object or another magnetic field; see also

magnetic loop antenna Type of (also mag loop for short) whose is bent into a roughly rectangular or curved into a roughly circular shape, to be operated from within a relatively small area, such as a house or backyard; see also

magnetic loop antenna

magnetizing current

in the winding of a when no is connected to the (the secondary is an open circuit), to maintain mutual magnetic flux in the core; see also
Note: the associated due to the applied and the magnetizing current is and expressed in VARs

magnetosphere Area of space near the earth in which the behavior of charged particles are often controlled by the earth's magnetic field; see also

magnetosphere diagram

magnetron oscillator High- or made from a with a specially shaped surrounded by a permanent magnet, to create an interaction between the resulting stream of electrons and the magnetic field; see also

magnetron oscillator

Maidenhead Locator System

See

mains power

See

malicious interference

See

MARA

Mercury Amateur Radio Association : group of (mostly LDS) sub-groups and that provide communication around the world, but is not officially associated with, or sponsored by, the LDS Church; see also the main and a regarding MARA
Note: MARA was once sponsored and promoted by the LDS Church, but has since been replaced by

Marconi, Guglielmo Italian inventor and engineer, labeled by many as the Father of Wireless Telegraphy, the Father of Radio, and even credited with the invention of the , was known especially for his pioneering work on long-distance radio transmission; see also

Guglielmo Marconi

maritime mobile amateur radio

operation on any manned vessel afloat at sea, and not an inland waterway; see also and what maritime mobile means to the ARRL

mark

The higher of a signal, or the lower frequency of an signal, a identifying the 1 bit

MARS

Military Auxiliary Radio System : (formerly Military Affiliate Radio System and Auxiliary Amateur Radio System) program sponsored by the US Department of Defense and serving as a civilian auxiliary to the US Army, Air Force, (at one time the US Navy), and Marine Corps, containing licensed who are interested in assisting the military with communication on a local, national, and international basis, supplementing regular military communication; see also and the Army MARS website and the Navy MARS website

MARS/CAP modification / MARS/CAP mod

Modification made to a , enabling transmissions outside the limits of the , originally for use on military bands used by and operation, but can also extend to bands reserved for , , , Maritime, Aviation, and other communication

mast Pole, stick, or other (typically rigid) structure used to support an , , , and/or other external components (usually unrelated to the type used on ships and other watercraft), and often held in place by ; see also and

mast supporting a J-pole and its feedline

match / matching

• See for the general practice or theory of matching
• See for the -specific application of matching

matchbox / match box

Older slang for

Maxim, Hiram Percy American pioneer and inventor who founded the in response to the lack of that could pass via at the time; see also

Hiram Percy Maxim

maximum permissible exposure

Greatest amount of to the human body for a given legally allowed by the ; see also MPE on FCC

maximum symbol rate

See

maximum usable frequency

Highest that can be used for transmission between two points by through the , affected by location on Earth, distance between , season of the year, time of day, and can be reduced dramatically by a of 5 or greater ( as a result of solar radiation); see also and

mayday

International distress call derived from the French m'aider or m'aidé, meaning help me; see also
Note: the term mayday is typically recognized as an emergent (immediate threat to life) distress call, while is more often recognized as an urgent (dangerous situation that is not immediately life-threatening, but could become emergent) distress call

mc

MC4 connector Multi-Contact, 4 mm : model name for a water-resistant (IP68) and high- that is easy to connect but intentionally difficult to disconnect (to prevent accidental disconnection), commonly used for connecting together; see also and

MC4 connectors

M connector

• Alternate model name (also called M-type connector and type M connector) often used on for a or
• Model name for the Japanese version of a or , but with metric threading

MCW

modulated continuous wave : tone- () , permitted only on and ; see also

MDS

minumum discernible signal : see

mean power

See

mega

Prefix, or units modifier, to indicate × 1,000,000 or × 10⁶, and is abbreviated M

megacycle

Outdated term for megahertz (MHz)

mesh network

Nickname for

message

• Any information communicated between two or more points (people, equipment, components, sites, etc.), regardless of content, format, , or type ( or , for example)
• A piece of information (also called payload) contained or embedded in a larger grouping of data, such as a or frame

metal-oxide varistor

See

meteor scatter Brief of , particularly those between 30 MHz and 50 MHz, as they are by the ionized trails of meteors in the of the ; see also and

meteor scatter

meter Instrument or device that measures a property quantity or quality, and typically presents the result on a human-readable display; see also and SI fundamental unit of length (metre in the UK); see also Name by which an is referred I often hang out on the

Analog meter

Digital meter

meter wave / meter-wave Visible act of greeting or salutation by causing the of another operator to sweep across its face, as though you are waving at the recipient Outdated slang for

Meter-wave

method of moments

Numerical computational method of solving linear partial differential equations that have been formulated as integral equations (in boundary integral form), useful for modeling ; see also

MF

medium frequency : overall range of 300 kHz to 3000 kHz, of which the () is a part; see also and the MF frequency designation in the RF spectrum

MF4

See

MFSK

multiple frequency-shift keying : low-rate transmission in which the signal is shifted between more than two to convey the information, with MFSK16 being most applicable to due to its exceptional performance in environments without the need for error correction; see also and

mic / mike

micro

Prefix, or units modifier, to indicate ÷ 1,000,000 or × 10^-6, and is abbreviated µ

microcontroller Computer on a single designed for embedded (complete, self-contained) applications, and which can replace complex digital circuitry; see also

microcontroller

microphone Device (often abbreviated mic or mike) that converts sound into an electrical signal; see also and

hand microphone

desk microphone

boom microphone

microphone symbol

microphone gain / mic gain / mike gain

• Quantity of electrical signal
• Control that allows modification of the amount of signal amplification

microphonics

Electrical or signal resulting from the mechanical vibration of charged component parts, similar to the way a transforms vibrations into electrical signals; for example, an undesirable change in due to mechanical vibration; see also

microprocessor Computer on a single designed for general purpose applications, such as a personal computer; see also

microprocessor

microstrip Type of that can be constructed as a precision printed circuit board lead separated from a by a substrate to provide constant interconnects at ; see also

microwave

Overall range of 300 MHz to 300 GHz, encompassing most of , , and , and typically limited to 1 GHz to 100 GHz for most applications; see also and the RF spectrum

military time

Alternate term for 24-hour clock, in which local time is represented by twenty-four equal-length but uniquely designated time periods per day; see also
Different formats representing 7:23 pm in most of Utah, for example:
• 1923 (military use)
• 19:23 (non-military use)
• 1923R (military use, with time zone suffix)
  Note: the military notation with the Z (zulu) suffix is equivalent to time

milli

Prefix, or units modifier, to indicate ÷ 1,000 or × 10^-3, and is abbreviated m

mini-8 / mini 8

See

mini-RG-8 / mini RG-8

See

minimum discernible signal

See

minimum-shift keying

Type of transmission that uses a continuous- method of by encoding each bit as a half sinusoid; see also

MININEC / mini-NEC

Variation of the design modeling and simulation software; see also and

mis-match / mismatch

See

mismatch loss / mis-match loss

Total of an signal (or total measured potential attenuation) in a , to which an attached () exhibits an impedance that does not match that of the transmission line, after the losses are added up for all possible (indeed, infinite) trips of the signal, and often measured in ; see also
Caution: this Wikipedia article contains several widely held myths, but its link is provided here because it also presents some appropriate facts and references

mixer

Circuit that converts an signal of one to that of another frequency in a ; see also

mixing

• Act of combining an signal of one with a signal of an , to create a new signal (often, the product, as in ), for which further processing, manipulation, and are easier to design for and work with
• Act of (intentionally or otherwise) combining any two signals, resulting in the product (multiplication) of the two

MM / /MM

See

MMIC monolithic microwave integrated circuit : that performs functions such as , , and at (300 MHz to 300 GHz) ; see also

MMIC chip

mobile that is usually too large to normally carry around by hand, but small enough to install in a vehicle; can also refer to any transceiver in your vehicle, regardless of size My mobile is a FT-8800R Transmitting while traveling I'm mobile at the moment Primarily for use in or on vehicles I have a mobile

2 m mobile transceiver

mobile station

that is installed in or on a vehicle; see also

mode

• Short for method, classification of (emission type) format (along with specification and operating ), such as , , , and ; see also
• Pair of and used to communicate with a particular
• Device operating configuration, such as mode or mode or mode for a , or Bypass mode for a

modem Device (from modulator / demodulator) that can encode () an or signal for transmission, and decode () a received signal into an audio or data signal; see also

external modem

internal modem

modulation / modulate Process of varying one or more properties of an signal according to an information signal, such as your , in preparation for transmission, by combining them as a product (multiplying the functions, as in f(x)g(x) together) for or a composite (one signal as a function of the other, as in f(g(x)) combined) for , as examples

modulation examples

modulation envelope Signal created by connecting the peak values of a signal (boundary curve that encapsulates a modulated of an signal); see also

modulated signal with its envelopes

modulation index

• : ratio of the signal amplitude to the amplitude; see also
• : ratio of the from the frequency to the signal frequency; see also
• : difference in and the unmodulated signal; see also

Molex connector Model name (from Molex) for a , once commonly used to supply power to equipment; see also and Note: Molex produces numerous different connectors, but this particular model has probably been the most common DC connector found on older amateur such as the TS-450S and FT-840 and IC-746Pro

Molex connector and pins

Molex T connector

See

monitor / monitoring

• Invitation for any other operator to talk with you
  KI7ABC monitoring
• Announcement that you are simply on a in case somebody needs assistance, but not actively participating in a conversation; see also what it means to monitor a frequency and what monitoring means to the ARRL
  I'll be and monitoring
• Act of listening on a frequency, or multiple frequencies, in search of communication activity
• Type of receiving in which all information transmitted on the packet is displayed by the listening

monopole antenna Class of consisting of a (typically) straight rod-shaped conductor, often perpendicularly over a conductive surface called a ground plane; see also

monopole antenna

monostable multivibrator

Circuit whose signal switches momentarily to the opposite binary state, then returns to its original state after a set time (also known as a one-shot); see also

moonbounce / moon bounce

See

Morse code Spoken or written language characters represented by a series of dots, dashes, and spaces (more formally International Morse code and often simply code), and in typically transmitted by a known as ; see also and the elimination of the Morse code requirement on amateur radio examinations

Morse code abbreviation

Abbreviation or shortened version (one to four characters) of a commonly used word, originally for brevity in sending a message by , but also used in as part of the spoken or written vocabulary; see also and

MOSFET metal-oxide-semiconductor field-effect transistor : (so-called due to its original basic construction of a metal layer deposited on an —usually silicon dioxide— layer, which in turn is deposited on a layer) is a type of whose construction allows for high-speed switching at very low power consumption; see also

MOSFET

MOSFET symbols

motional capacitance

Effective in the series leg of the equivalent circit for a

motional inductance

Effective in the series leg of the equivalent circit for a

motional resistance

Effective in the series leg of the equivalent circit for a

motorboating

Slang for the undesirable rumbling sound that results from low- feedback, once prevalent in -based ; see also

Motorola connector Generic name for a used for scanner receivers, primarily in applications; see also

Motorola coax connector

mount See Installation, connector, or enclosure that allows the attachment of one piece of equipment to another, often more stable or environmentally protected fixture Install, attach, or connect one piece of equipment to another, either directly or by means of a bracket, cage, or other assembly

vehicle-mounted HT

enclosure-mounted HF rig

MOV

MPE

MSK

MSK144

minimum-shift keying, 144 MHz : type of brief transmission used for at 50 MHz or higher (the MSK144 sh used for communication at 144 MHz or higher); see also MSK144 on WSJT-X

M type / M-type

See

mud

Slang for at or below the current level, often used as part of down in the mud, or simply, in the mud
I tried to him, but his signal was down in the mud

MUF

multiband / multi-band

• that will effectively support transmission and reception of signals on more than one
• that can transmit and receive signals on more than one
• Superset of terms that define both transmission and reception support for more than one , such as dual-band (two bands), tri-band (three bands), and quad-band (four bands)

multicoupler / multi-coupler

Device (also called splitter) that distributes a received signal (typically by ) to a variety of , often as part of a site; see also

multihop / multi-hop

More than one ; see also

multilateral agreement / multi-lateral agreement / multilateral arrangement / multilateral operating agreement

Set of rules agreed upon by two or more countries to authorize radio operation in all applicable countries by a person who is not a citizen of ( to) one or more of those countries

multimeter Instrument that combines the functions of a to measure electric , an to measure electric , and an to measure , usually with a digital readout (called a DMM, or ); see also and

multimeter

multimode / multi-mode

• Device, such as a or that is capable of , , , and possibly more, operation
• Antenna, transceiver, or other device (meter, tuner, etc.) that can be configured to operate in more than one way

multipath / multi-path

Type of or caused by a signal arriving at a from different-length paths at slightly different times, resulting in part of the signal from one path canceling part of the signal from another (destructive interference), or enhancing part of the signal from another (constructive interference); see also
Note: the term has at times been used synomously with multipath, but more typically refers to replica television images appearing offset in intended position, often caused by signal multipath

multiple receiver / multi-receiver

See

multiplier

Circuit in an that generates a (multiple) of a lower signal to produce the desired operating frequency; see also

MURS

Multi-Use Radio Service : set of by the for , -free, and short-distance use; see also and a chart of assigned MURS frequencies [PDF]

mutual inductance

Magnetic between two that allows flowing in one inductor to cause (induce) current to flow in the other nearby inductor, which a exhibits when an presented across its primary winding results in a voltage appearing across its secondary winding; see also

MW

medium wave : section of the that is also known in the US as the band; see also

N

for

NAND gate Digital logic circuit () in which all its logic input signals must be asserted ("TRUE", high, or 1 state) to produce a non-asserted ("FALSE", low, or Ø state); see also

NAND gate symbol

narrowband FM / narrow band FM / narrow-band FM / narrow FM

signal whose peak is much larger than the of its signal, typically twice as large, and is the bandwidth type used in , , and most radios; often regarded as being limited to 12.5 kHz; see also and

narrow-band roofing filter

See

national calling frequency

Subset of that is recognized across the US and reserved for incidental use, requesting non-urgent assistance, true , testing, and whose use in making casual or first-time contacts is encouraged
They are assigned as follows:

	Frequency (MHz)
6 m	50.125	SSB
6 m	50.400	AM
6 m	52.525 †	FM
2 m	146.520 †	FM
1.25 m	223.500 † *	FM
70 cm	446.000 †	FM
33 cm	906.500	FM
23 cm	1294.500 †	FM

† part of the proposed
* Some question whether this 1.25-meter frequency has been officially adopted as an actual national calling frequency

National Radio Quiet Zone

Large rectangle of land straddling the borders of Virginia and West Virginia surrounding the National Radio Astronomy Observatory, where radio transmissions are strongly restricted, to facilitate research for military intelligence and scientific advancement; see also

National Traffic System

Network of and others organized for the purpose of throughout the US and Canada during times of or during a drill; see also and

NATO phonetic alphabet

See

NB

NBEMS

Narrow Band Emergency Messaging Software : open-source software that allows radio to reliably send and receive using a computer and radio pair; see also and

NC

• no connection : common pinout label for an or other electronic package, to indicate that the internal circuitry presented by the conductor so labeled is not connected internally, or should not be connected outside the package, to any meaningful electrical path

N connector Neill : weatherproof, gendered 50 Ω (also called N-type connector and type N connector) often used on for applications; see also

N connectors

NCS

near-field / near field

View of a for an or other object capable of , as observed from a sufficiently close proximity, to examine the effects of nearby influences on the field, including those from the field itself; see also
• (for a more technical description)

near-vertical incidence skywave / near vertical incidence skywave Type of technique that promotes highly reliable short-range communication by transmitting its signal upward instead of outward, typically available only for the and (between around 2 MHz to 10 MHz); see also and Type of (once called cloud warmer and cloud burner) used primarily for short-range communication by much of its signal straight up

NVIS antenna drawing

NEC

• Numerical Electromagnetics Code : popular design modeling and simulation software that uses the approach for its calculations; see also
• National Electrical Code : regionally adopted American standards and guidelines governing electrical safety; see also
  Note: in spite of its name, the NEC is not adopted nationally, nor is it federal law

negative

no; see also

net

• Short for network, gathering of radio who are organized socially or for a common interest, such as preparedness; see also and how to join a net
  Are you planning on checking in to the net tonight?
• Short for
  This is KI7ABC...back to net

net control / net control station

Managing of a , charged with accepting check-ins, coordinating resources, and directing communication , often under the direction of a in a local net or during a drill or net

net manager

Person who establishes a particular (by coordinating and then advertising its frequencies and times, assigning a , and overseeing its general operations) and sets forth the and content of the net, and dictates when to start and terminate the net

network

• Arrangement of interconnected electrical components that serve a combined purpose, such as , , or ; see also
• Group of , operators, or other entities interconnected in some way to provide a specific service or function, to other group members or those outside the group, such as
  • digital network : members connected by computers or
  • social network : members gather to share a variety of information
  • network : members collaborate to provide aid, comfort, transportation, training, and other needs

newbie

See

NF

NFM / N-FM / NBFM

NiCd / Ni-Cd / nicad nickel-cadmium : type of that exhibits heavy memory effect and is known for low energy density but longer cycle life compared with that of batteries and relative low cost compared with that of batteries; see also

NiCd batteries

NiMH / Ni-MH nickel-metal hydride : type of that exhibits little memory effect and is known for high energy density compared with that of batteries and relative low cost compared with that of batteries; see also

NiMH batteries

niner

Alternate way of the numeral 9
My is alpha-juliet-niner-romeo... ?

NMO New Motorola : model name for a common , primarily for applications; see also

NMO through-hole mount

NMO trunk-lip mount

NMO magnetic mount

node

Point of interest in a particular system
• : dedicated computer and associated hardware that to the internet; see typical IRLP node
• : internet-capable device running software that to the internet
• : dedicated router that to a local network that's attached to the internet; see mesh node
• : point along a where the amplitude is at its minimum

noise

Any undesirable signal or any signal other than the one expected or being monitored, such as , , , or ; see also

noise blanker / noise blanking / noise-blanker

Circuit that high-amplitude, wide-band (spikes, pulses, etc.) at the without introducing ringing (which often plagues ) by the signal only during the duration of the noise pulse
Note: because the two are often confused, filters the unwanted signal by limiting amplitude while NB filters it by attenuating the signal for the duration of the noise

noise figure

Ratio (often abbreviated NF) of the generated by a with respect to the , and expressed in , the lower the value, the better the receiver performance; see also

noise floor

Sum of the from all sources within a system of interest, plus other unwanted signals, such as , and the lowest of which is considered the ; see also

noise squelch

See

nominal

By name only; for example, a D cell is typically labeled "1.5 volts" but might actually measure at 1.487 volts, so "1.5" is its nominal value; see also

non-inverting

Type of non--specific that re-transmits a received signal at the same passband offset from the end of its as that of the received signal, and on the same end of the passband; see also and
Example: suppose that a linear transponder's receive passband is 432.000 MHz to 432.100 MHz, and its transmit passband is 146.000 MHz to 146.100 MHz. If it receives an signal on 432.008 MHz (therefore using a passband offset of 432.008 MHz − 432.000 MHz = 0.008 MHz), the transponder will re-transmit on (146.000 MHz + 0.008 MHz = ) 146.008 MHz, and in upper sideband

non-ionizing radiation / nonionizing radiation

that does not possess enough energy to ionize (free electrons from) the atoms and molecules of living tissue, thereby unable to cause genetic damage; see also and

non-volatile

Will maintain its stored information, even if its is removed, especially in the case of computer memory; see also

noob

See

NOR gate Digital logic circuit () in which any of its logic input signals can be asserted ("TRUE", high, or 1 state) to produce an non-asserted ("FALSE", low, or Ø state); see also

NOR gate symbol

northern lights

See

notch filter with a very narrow , or in other words, has a high , to reduce from signals in the ; compare with

notch filter graph

NOT gate Digital logic circuit () in which all its logic output signal is reverse-asserted from that of its input signal; see also

NOT gate symbol

novice

• Novice : former entry-level radio
  Decades ago I had my start in ham radio with a Novice class license
• Beginner, or person who is inexperienced at a craft or skill (also called newbie, , green horn, and neophyte); see also
  I'm a novice when it comes to building

NPØ / NP0

negative-positive-zero : ceramic classification (equivalent to the EIA category CØG) indicating the ability to maintain its (in the negative direction or positive direction) with a large tolerance for temperature change (Ø °C change), which can be used to reduce thermal drift in ; see also

NPN

See

NPOTA National Parks on the Air : event during 2016 in which radio located in pre-selected sites attempted to contact as many other NPOTA stations as they could, in conjunction with the National Park Service centennial celebration, subject to ARRL NPOTA rules; see also and the main

NR

• noise reduction or noise reducer : button or setting on many modern (sometimes labeled ) that enables a special designed to reduce through
• Initials of the author of this glossary

NRQZ

NTS

NTSC

National Televsion System Committee : name for color signals, which transmit 30 frames per second, each frame of which is made of 525 lines, and which typically requires approximately 6 MHz of when transmitted on the ; see also

n-type / N type Type of doped material that contains excess electrons in the outer shell of electrons (larger electron concentration than concentration), resulting in a net negative charge and making electrons the majority carriers in this type of material; see also

n-type semiconductor effect black circles = electrons white circles = holes

nube

See

null Area or direction in an in which its signal is almost entirely canceled or nearly non-existent; see also Quantity of little or no signal

NVIS

NXDN

Next Generation Digital Narrowband : open communication standard (jointly developed by and ) designed as an advanced digital system, including encryption, , and voice; see also