Radio in general is a technologically advanced field, and those who have obtained their ham radio licenses
can tell you that learning some of that technology can be challenging. We've collected some links that can
help you understand both the basics behind radio and some of the in-depth engineering that goes into the
physics of radio, along with ways to improve your setup.
Hover over a word in
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Quick Links
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Just starting out in ham radio
Antennas
[general,
VHF-UHF,
HF]
Grounding and bonding
[general,
suppression,
references]
Propagation
[general,
solar,
other]
Signal transmission
[tuners,
transmission lines,
reflection,
return loss]
SWR
[education,
effects,
myths,
other]
Connection
[coax,
connectors,
wires,
loss]
Technology
Chokes, filters, baluns
Digital
Issues
[noise,
shack RF,
damage,
other]
Good-to-know
[general,
tips,
how-to,
best practices,
other]
Solar
[general,
panels,
charge controllers,
batteries,
other]
Repeater
[general,
isolation,
other]
Other equipment
[general,
test / analysis,
other]
Specialized
Electrical
[electricity,
batteries,
circuits,
electronics,
advanced,
other]
For beginners
[electronics,
electromagnetics,
RF,
other]
Tubes
[theory,
amplifiers,
other]
Presentations
Sane preparedness
Safety
[general,
medical,
other]
Advanced topics
Antennas
PhD required
Physics
[general,
electrodynamics,
other]
Other
Debunked myths
Other
[glossaries,
Hallas,
other]
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Just starting out in ham radio
Antennas
General
VHF / UHF
HF
Dipole
End-fed
Radials
Random-wire / long-wire
NVIS
Other
More
Grounding and bonding
General
Suppression
To aid searching, devices meant to suppress electrical surges are labeled by a variety of names:
lightning arrester / lightning arrestor / lightning suppressor / lightning protector
surge suppressor / surge protector / surge arrester / surge arrestor
discharge unit / discharge device
coaxial protector
Research into surge suppression devices
[PDF] (John White VA7JW, 09-30-2013)
References
Propagation
General
Solar
Other
How weather affects radio propagation
(it can affect the conditions, but no set answer fits all)
-
Essentially, rain , snow, and fog typically affect frequencies over 2 GHz
very heavily, while affecting frequencies under 30 MHz very little
-
On the other hand, lightning is the single largest contributor to
atmospheric noise
-
Furthermore, temperature inversions can result in tropospheric ducting,
which typically affect frequencies greater than 90 MHz
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Signal transmission
Tuners
Transmission lines
Reflection
Reflections III
(Walter Maxwell W2DU, Third Edition) [PDF]
and a
link on my website to his book
and
some reviews
Page 1-2 : All power reflected from the feed line-to-antenna mismatch is conserved, not dissipated
Page 1-5 : Reflected power is not dissipated in the transmitter
Page 1-9 : A tuner allows for greater bandwidth for a given antenna
Page 7-1 : Maximum efficiency is obtained with a perfect match
Page 7-3 : Why match at the feed line input?
Page 7-3 : A transmitter can be damaged by overloading or underloading
Page 13-3 : The antenna tuner really does tune the antenna to resonance
Page 17-1 : A tuner changes the antenna impedance by conjugate matching
Page 17-2 : Feed line length does not matter if using a tuner
Page 17-3 : The logical place for a tuner is at the operating desk, not at the antenna
Page 19-11 : The Maximum Power Transfer Theorem
The myth of reflected power
(excellent General-level article, including the math, by Davide Achilli, IZ2UUF)
The myth of high SWR causing feed line radiation
(excellent General-level article, including the math, by Davide Achilli, IZ2UUF)
Conjugate match myths
(Steve Stearns, K6OIK, 10-16-2011) [PDF]
Reflected power will NOT damage your radio
and
his original page
(good reading, but sloppily written, by Steve Ward, WC7I)
SWR and reflection
(Darrin Walraven K5DVW, QST 11-2006)
Return loss
SWR
Information on SWR can be categorized under antennas, transmission lines, and reflections, among
other things, but is a topic often singled out for discussion, and so deserves its own section
Education
Effects
Myths
Other
Connection
Coaxial cable
Connectors
Wires
Loss
Technology
Chokes, filters, baluns
Digital
Issues
Noise
Shack RF
Damage
Other
Good-to-know
General
Tips
How-to
Best practices
Other
FT8 on 10 meters, on a budget
(Tom Costello KD9CPB)
Signal attenuation due to vegetation
(graph photo from ITU)
2-meter example through a leafy, 22-foot diameter tree:
At 146 MHz, attenuation for a vertical antenna is about 6 × 10-2 dB/m, or
−0.06 dB/m = 1 − 10-0.006 = 0.0137 attenuation/m = 1.37 % att/m
For a 7 m diameter tree with thick leafage : 7 m × 1.37 % att/m = 9.6 % att
5-watt HT : 4.5 watts get through / 20-watt mobile : 18.1 watts get through
Solar
General
Panels
Charge controllers
Batteries
Other
Repeater
Other equipment
General
Test and analysis
Other
Specialized
Electrical
Electricity
Batteries
Circuits
Electronics
Advanced
Other
For beginners
Electronics
Electromagnetics
RF
Other
Tubes
Presentations
Sane preparedness
Safety
Advanced topics
Antennas
PhD required
Physics
General
Electrodynamics
Maxwell's Equations
and
on Wikipedia
MathJax
reference (math formatting)
1. Gauss's Law
and
on Wikipedia
The total electric field exiting a closed surface is proportional to the enclosed charge
Implies Coulomb's Law, that charge results in a proportional electric field
2. Gauss's Law for Magnetism
and
on Wikipedia
The net outflow of a magnetic field through a closed surface is zero
3. Faraday's Law of Induction
and
on Wikipedia
A changing magnetic field will induce a voltage in a conductor exposed to the field (Faraday's Law)
A changing magnetic field will produce a changing electric field (Maxwell-Faraday Law)
4. Ampere's (Circuital) Law
and
on Wikipedia
An electric current will produce a magnetic field (Ampere's Law)
A changing electric field will produce a magnetic field (Maxwell's addition)
(A changing magnetic field will produce an electric field)
(A changing magnetic field will produce a current in an exposed conductor)
Oersted's Law
-
The magnetic field lines encircle the current-carrying wire (in the direction
dictated by the right-hand rule)
-
The magnetic field lines lie in a plane perpendicular to the wire
-
The magnetic field direction reverses if the current direction is reversed
-
The strength of the field is directly proportional to the magnitude of the current
-
The strength of the field at any point is inversely proportional to the distance of
the point from the wire
Biot-Savart Law
and
on Wikipedia
An electric current creates a proportional magnetic field
Lenz's Law
and
on Wikipedia
A current that is induced in a conductor by a changing magnetic field will oppose
changes to the magnetic field that produced it
Coulomb's Law
and
on Wikipedia
Charge results in an electric field \(F = \frac{1}{4\pi\epsilon_o}\frac{qq_o}{r^2}\), and
\(F = q_0E\); therefore, \(dE = \frac{1}{4\pi\epsilon_0}\frac{dq}{r^2}\)
The force of one point charge acting on another point charge is proportional to the
inverse-square of the distance between them
Electromagnetic wave equation
Second-order partial differential equation that describes the propagation of electromagnetic
waves through a medium or in a vacuum
Other
Other
Debunked myths
Folded dipole myths
(Tom Rauch W8JI)
Busting old myths surrounding end-fed half-wave antennas
(they do work : by Peter Waters G3OJV)[YouTube 13:10]
The Myth of RF Ground
(Ward Silver, NØAX, QST, 01-2015)
The myth of reflected power
(excellent General-level article, including the math, by Davide Achilli, IZ2UUF)
Coaxial cable length does not change antenna SWR
(by Gordon Hudson, AD5GG)
My feedline Tunes My Antenna!
(03-1956, by Byron Goodman, W1DX)
He also mentions that SWR will not change with transmission line length
Collection of busted myths
(ARRL, Terry Graves, K7FE, 2009)
SWR myths and mysteries
[PDF] (Andrew Barron, ZL3DW, 09-2012)
Modern batteries are safe to store on concrete
Other
Ham radio glossaries
Joel Hallas articles in QST
Other
General atmospheric opacity chart
Questions? Ask
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