[EMP Button]
The Myth of EMP
The subject of EMP, or Electromagnetic Pulse, is not immune to the enormous amount of mis-information available on the web today. Thanks largely to the widespread evangelization of emotionally promoted rumors in the name of family and emergency preparedness, many well-meaning enthusiasts are driven by misguided beliefs, often leading them to over-spend on unnecessary gear or become involved in questionable readiness practices. The goal here is to educate you and help de-bunk the prevalent myths surrounding this oft-misunderstood topic by providing you with good, useful knowledge in plain English.

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Abstract (this article, in a nutshell)
    Asking what might happen to your ham radio equipment during an EMP is like asking what might happen to your dog if your house got bombed. Assuming you have a dog, and your dog's at home, and it's sitting somewhere unprotected, what might happen to him can range from nothing at all, to getting blown to bits.

    The short is, depending on how strong the pulse is, and how exposed your equipment is to the pulse, your ham radio equipment might not be affected at all, or it can get burned to a crisp. The only two types of significant EMP your equipment will ever be exposed to will be nuclear-made and solar-made. The nuclear-made event is so unlikely that it's not worth the time or money to protect any of your equipment from such an event. Besides, if a detonation was close enough to actually do your equipment any damage, saving your gear will be the least of your worries.

    A solar-made EMP is much more likely, but the fact is, the effect of even a large solar-made EMP is so minimal that neither you nor anybody on earth will barely notice it. And if it's large enough to notice, chances are you'll have 20 to 40 hours to prepare for it. And to prepare for it, just put your ham radio equipment in your car, assuming your car has a steel body. For the rest of your appliances, if you're truly concerned, just unplug them.
[Puppy Chewing]
What exactly is EMP?
    EMP, or electromagnetic pulse, is a short, sudden, high-energy burst of electromagnetic radiation, often at a frequency range that spans much of the known spectrum. In other words, EMP is a very strong and short-lived radio signal with a very large bandwidth. It shouldn't be confused with radioactivity, in which radioactive material ejects nuclear particles and radiation in a process of nuclear decay, instead of a single single burst or pulse of electromagnetic energy.
[EMP Sinusoid]
The problem with EMP
    A nearby radio station or cell tower transmits a radio signal that's easily picked up by your radio's external or cell phone's internal antenna. That's because your metallic antenna is designed to convert the radio signal into a voltage that is then carried into your radio or cell phone circuitry. And the stronger the radio signal (because you're closer to the radio station or cell tower, or its signal strength has increased, for example) reaching your device, the larger the voltage that will be created, hopefully resulting in a clearer and louder sound.

    Any metallic object (think towers, buildings, aircraft, power lines, vehicles, houses, appliances, and computers) subject to a large-enough EMP burst can act like an antenna, bringing destructive voltage pulses to its internal circuitry, especially sensitive micro-electronics. Many modern products previously manufactured as purely mechanical now incorporate microchips, microcomputers, cameras, Bluetooth, and Wi-Fi for monitoring and control, leaving many of these devices vulnerable to the effects of a strong EMP event.

    The result of a large voltage surge being applied to sensitive micro-electronics can range from the inconvenience of a fried electronic Mickey Mouse watch, to a disabled wide-area communication network. But EMP effects on even small electronic devices can be life-threatening if the device is an implanted pacemaker, for example.

    Because of the enormous amount of signal strength in these surges, significant electromagnetic pulses can appear in unpredictable power levels, making them very difficult, if not impossible, to control. In spite of all this, an EMP pulse will not harm humans or household pets.
[Ham Radio Antenna] [Microelectronic Device]
The two most significant EMP sources
    An electromagnetic pulse can be small or powerful. An example of a small pulse can be heard as static on your radio from flipping a powered light switch in the room. Lightning, a much larger pulse source carrying an enormous amount of charge, can also be heard on your radio as static, often from many miles away.

    But even lightning, as powerful as it is, being able to destroy household appliances, your house, or even you, does not produce an electromagnetic pulse at a level that poses a widespread threat. Its destructive properties are mainly high electrical current, extreme heat, and intense light, not to mention the deafening thunder you might hear if you're near such a strike.

    If we narrowed down a list of EMP sources that could pose a widespread threat, it might include the following:
      unusual solar activity
      nuclear detonation
      pulse generator
    A pulse generator is no more than an object or instrument that produces an electromagnetic pulse, for testing, experimental, or malicious purposes. While still possible, because such a device typically requires a tremendous amount of energy to create a significant surge, the likelihood of using one to generate a pulse large enough to pose a viable threat is quite remote. So, that leaves us with the first two sources.
[Lightning]
You will likely never experience a large, man-made EMP
    Man-made EMPs can be realized in two ways, either deliberately or incidentally. A deliberately created pulse is one that's formed specifically for experimental, military, or nefarious (evil) purposes. Experimentation often requires the reproduction of destructive forces and environments, typically in an effort to test defenses against attack or the ability to prevent such an attack. These experiments are normally conducted at sites or in environments away from the general public, so your encounter with those pulse events is very unlikely.

    An EMP created deliberately for malicious purposes has a much greater opportunity of affecting the public if the required energy is sufficiently available. But the energy required to produce an effectively destructive pulse is so great, and the accompanyinng equipment so expensive, that it's out of the reach of most would-be perpetrators. One possibility is a military EMP generator (e-bomb, or NNEMP), which typically presents less than a millionth the pulse energy as that of a nuclear source, but has also proven effective for attacking electronics installations, disrupting communication.

    An incidentally created pulse is generally a side-effect of another, significant event. In the man-made case, that typically translates to a nuclear source, as in a weapon detonation. Known as a nuclear EMP (NEMP), this pulse is large enough to cause widespread damage to vulnerable and exposed electronics. But nuclear weapons are currently only available to a few governments that can afford the extreme cost of researching, developing, and launching such an instrument.

    Most nuclear detonations must be close enough to the ground to produce noticeable damage. And if a detonation was to occur close enough to ground to produce such damage, chances are that people will be killed by the radiation, and their electronics incinerated, by the resulting heat. However, the geographic area surrounding the deadly radiation and heat zone of such a closely detonated nuclear weapon will most likely be heavily affected by EMP, the size of the area dependent on the terrain and weapon capability. Those still alive in that area of vulnerability will likely experience the loss of device function as a result of the huge pulse. Your device can fail in that case because of direct EMP exposure or because it's simply plugged into the grid, which can deliver the pulse electrically into your home, potentially destroying everything plugged into it.

    If calculated properly, a nuclear device detonated in the upper atmosphere can produce a high-altitude EMP (HEMP), which can affect an even larger area, due to the interaction between the high-energy free electrons produced by gamma radiation, and the Earth's magnetic field, resulting in a magnification effect of the destructive pulse over that which could have been produced at lower altitudes.

    Still, the likelihood of such a nuclear scenario is extremely small, especially because there are so many safeguards in place that prevent a nuclear attack from even getting close to American airspace. So, investing a large amount of time and resources into protecting against such an event is left to entities (governments, military, large corporations, etc.) that can afford to develop and maintain the infrastructure. For the rest of us, it's probably best to install some small and inexpensive measures to protect against an EMP if we're truly concerned about it.
[Experimental Pulse Generator]
Testing a pulse generator
[Thermonuclear Cloud]
You will rarely experience a solar-caused EMP
    Also known as a space-based source, an extra-terrestrial EMP typically originates as a solar flare in a magnetically weak but localized solar region, which, if its material is cast off into space instead of returned to the surface, becomes a CME (coronal mass ejection), which can form a geomagntic storm as the shock wave or solar wind from the ejecta reaches the earth's magnetosphere.

    Relative strengths of solar flares are classified as follows:
      Class Strength
      A < 10-7 pW/m2 X-rays (1 to 8 Å)
      B 10 times Class A
      C 10 times Class B
      M 10 times Class C
      X1 10 times Class M
      X2 2 times Class X1
      X10 10 times Class X1
      between X28 to X45 Solar Storm of 1859
      (the Carrington Event)
    Solar flares weaker than M-class do not noticeably affect the earth

    Can a strong, extra-terrestrial EMP originate elsewhere? Yes, of course it can, but that's very unlikely, so the sun remains our largest source for practical EMP concern.
[Solar Flare Animated]
How far should you go to protect your equipment from the effects of EMP?
    The short answer is that you really don't need to do much to protect your electronic gear from a direct EMP burst. The longer answer is that it will depend on how sensitive your electronics are to an electromagnetic burst and how large a burst you want to protect against.

    Unfortunately, many point to the US military as an example of the extent of protection that needs to be put in place, in order for their equipment to withstand a specified level of electromagnetic pulse attack, solar or man-made. Our military is charged with the huge responsibility of defending and protecting our government, our infrastructure, and our citizens against attacks, and they do so to the best of their ability with the resources available to them. Comparing their responsibility and resources with those of an individual is unfair at least and nonsense at worst. We cannot hope to provide the level of protection they can, but then, we also don't need to.

    An EMP originating from a large-enough solar flare can destroy, if not temporarily disable, household electronic devices, such as cell phones, radios, computers, televisions and monitors, home control devices (burglar alarms, cameras, thermostats, etc.), internet access gear, and game consoles. Fortunately, most of these can be easily protected from an average solar EMP event by simple shielding using metal containers.

    Containers that provide effective EMP shielding against an averagely large solar attack include your car, your refrgerator, aircraft, a shipping container, and your house (if it's covered with aluminum siding.) Some household metal containers can also be used as good shields, such as paint cans, metal garbage cans, and even a couple of layers of aluminum foil.

    You mean you can simply leave your radio in your car during an EMP attack, and it'll be ok afterwards? Yes, if your vehicle has a metal body (more and more cars these days have fiberglass bodies instead.) Wait...cars have computers and other electronic gear controlling them too. Does this mean their metal bodies will protect them against a direct EMP strike? Yes, they will.

    The other concern for EMP is through your electrical system. If a pulse makes its way onto the electrical grid, it can actually fry just about everything in your house that's plugged in. But wait...won't my circuit breakers take care of that surge of current coming into my home? Most likely not, because household circuit breakers are designed to open your circuit during a long-lasting surge, as in milliseconds. But by the time your breakers react to the intense, fast surge of an EMP, most of the energy will get through them, laying waste to your TV, your computer, your fridge, and everything else plugged into the wall. Going completely solar can get you off the grid, but that's expensive, and you'll still be somewhat vulnerable.

    Ok, but what about a nuclear-generated EMP attack? Well, since those are so rare, they're really not worth bothering about, so we'll let the military and the public utilities worry about that extremely unlikely event, and take the chance that we simply will never experience one.
[Faraday Cage Garbage Can] [Nissan Versa Note] [Electrical Substation]
So where did all the confusion come from?
    Fear-mongers. Rumor-mongers. Prophets of doom. Prep gear salesmen. Uninformed politicians and media celebreties. Paranoid neighbors and relatives.

    We humans tend to fear the unknown and the uncontrollable. Most of us know very little about EMP, and our reasons for fearing the worst is compounded when we learn of our inability to control this phenomenon, and more especially when we believe that our lives might be on a collision course with it. Admittedly, there are a lot of people who innocently promote EMP fears out of a sincere interest in helping others become aware of impending dangers they might encounter.

    Then, there are people who are willing to take advantage of your fear, in an effort to forward their own agenda or promote their product. Couple that with our current-day excitement over preparedness, and you have a recipe for dogmatic confusion.
[Paranoid Man] [Unscrupulous Car Salesman]
Summary
    An electromagnetic pulse is a real thing, and can be destructive to exposed and vulnerable electronic equipment. It can be manufactured and it can appear naturally, but the man-made EMP, such as that resulting from a nuclear detonation, has such a low likelihood of occurrence that it's probably not worth your time and resources to protect against such an attack. The naturally occurring EMP can most likely take place due to a very rare, but very strong solar flare.

    Still, if you're concerned about an EMP event, you can take small and inexpensive steps to protect your equipment, like placing your radio in your metal-body car, or unplugging your appliances when you know that an attack is pending. And depending on the particular type and proximity of the attack, you might not be around to enjoy your equipment, but that's beside the point.
[EMP Logo]
References
About Noji
    I am not an expert on EMP. Nor am I a physicist. I'm an engineer, having graduated as an Electrical Engineer in 1989 with a love of physics and a concern for preparedness. I don't know everything about EMP, but I know a little bit about it, and I know how to go about finding out the rest.

    I'm not a prepper, but I am LDS (Mormon), a licensed ham radio operator, and believe we need to be prepared...within reason.
[Albert Einstein]
Questions? Ask Noji

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