More on Electromagnetic Pulse

Over the weekend, I had the opportunity to speak with a retired military officer who worked in areas that involved EMP.  He provided me with several pieces of information.  He stated that the item that is most susceptible to damage from EMP is field effect and related transistors and that most unprotected electronics containing them would be damaged.  He feels that the typical garbage can Faraday cage (a metal garbage can lined with an insulating material) that is widely suggested on the web would work.

He said that batteries would survive without protection.  While he said, he has not seen any testing on solar panels he thinks that they would probably survive. However the controls and other electronic components attached to them would probably fail.  Apparently, the government has published very little on this subject and most of what they have is so technical it is above my pay grade.

He did refer me to one article that was published in 1979.  The problem with it is that it is dated and electronics have changed since then.  I have included it for general information since it is probably correct on electronics made prior to 1979.

The Effects of Nuclear War
Office of Technology Assessment
(May 1979)

Electromagnetic Pulse

Electromagnetic pulse (EMP) is an electromagnetic wave similar to radio waves, which results from secondary reactions occurring when the nuclear gamma radiation is absorbed in the air or ground. It differs from the usual radio waves in two important ways. First, it creates much higher electric field strengths.  Whereas a radio signal might produce a thousandth of a volt or less in a receiving antenna, an EMP pulse might produce thousands of volts. Secondly, it is a single pulse of energy that disappears completely in a small fraction of a second. In this sense, it is rather similar to the electrical signal from lightning, but the rise in voltage is typically a hundred times faster. This means that most equipment designed to protect electrical facilities from lightning works too slowly to be effective against EMP.

The strength of an EMP pulse is measured in volts per meter (v/m), and is an indication of the voltage that would be produced in an exposed antenna. A nuclear weapon burst on the surface will typically produce an EMP of tens of thousands of v/m at short distances (the 10- psi range) and thousands of v/m at longer distances (l-psi range). Air bursts produce less EMP, but high-altitude bursts (above 19 miles[21 km]) produce very strong EMP, with ranges of hundreds or thousands of miles. An attacker might detonate a few weapons at such altitudes in an effort to destroy or damage the communications and electric power systems of the victim.

See also  Glass Jars and Earthquakes

There is no evidence that EMP is a physical threat to humans. However, electrical or electronic systems, particularly those connected to long wires such as powerlines or antennas, can undergo either of two kinds of damage. First, there can be actual physical damage to an electrical component such as shorting of a capacitor or burnout of a transistor, which would require replacement or repair before the equipment can again be used. Second, at a lesser level, there can be a temporary operational upset, frequently requiring some effort to restore operation. For example, instabilities induced in power grids can cause the entire system to shut itself down, upsetting computers that must be started again. Base radio stations are vulnerable not only from the loss of commercial power but from direct damage to electronic components connected to the antenna. In general, portable radio transmitter/receivers with relatively short antennas are not susceptible to EMP. The vulnerability of the telephone system to EMP could not be determined.

Good source of information

I recently ran across an article entitled “EMP Myths” published by Jerry Emanuelson, B.S.E.E. (Bachelor of Science  at Futurescience, LLC.  The link to the article is  The home page of future science is  They have quite a few articles on EMP that are written in language that even I can understand.

After reading everything that I can find on this subject I have come to one conclusion that with all the different governments researching super EMP weapons no one but a few people in power know what these weapons are capable off.  I am preparing for the worst case, the loss of most electronics and hoping I am wrong.


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4 thoughts on “More on Electromagnetic Pulse”

  1. That the damage is done by an electromagnetic pulse. Unlike a radio wave that can be blocked by a faraday cage (basically a big screen enclosure) magnetism is much harder to block. Most of the EMP radiation from a nuclear blast is comprised of microwave and radio wavelengths generated when x-ray and gamma radiation interact with the upper atmosphere. Likewise for the Carrington Event — it was a massive solar flare, which is predominantly plasma. Both are shieldable. There are geomagnetic effects, I understand those are smaller in magnitude for nuclear blasts. No one knows, obviously, for the Carrington Event.

  2. Your military source is right, a garbage can can work. To really get the needed protection, however, you need to go beyond just putting things inside a steel trash can.

    If you are interested in this type of shielding issue, you might consider the book EMP Attacks and Solar Storms by Dr. Arthur Bradley.

    Dr. Bradley set a shielding goal of 50 dB from 100 kHz to 1 GHz. He reached the goal by a placing a device:

    –Inside a **regular** anti-static bag,
    –then inside a steel garbage can,
    –and then sealing the lid with copper tape.

    A steel trash by itself would probably work, but the issue is the lid seal. If it is at all loose, you lose almost all shielding. To be sure you’re OK, you need really wide copper tape to seal the lid.

    The problem with that option is that it is expensive (especially the copper tape, which is about $80/roll). It is also heavy, not easily portable, and not really “resealable”, unless you buy more tape.

    We wanted something that fits in a “go-bag” and also provides moisture protection. That is why we came up with our bags and got them tested at NASA. The 45 dB of protection is more than enough, beating unsealed garbage cans at frequencies above 250 MHz.

    Here’s a way to evaluate what you need for protection. Your shielding needs to:

    Create a closed “Faraday cage” that provides about 45 dB or greater shielding
    Be lightweight & portable, if used for portable electronics
    Be tough enough that it won’t be punctured easily
    Be easily sealed & resealed, so that you can check & use your backup devices.
    Be affordable enough that it won’t suck up all your preparedness money.


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