EMP does result from atmospheric tests, but it is of much lower amplitude.

The kind of attack we are discussing is HEMP (High altitude burst Electromagnetic Pulse). This has very different physics – see Wikipedia or the government pdf report.

Military equipment designed to fight on a nuclear battlefield is shielded against intra-atmosphere EMP. SO are other facilities such as some critical infrastructure – I’ve seen the EMP vault at our local Emergency Operations Center – it is underground, made of thick steel, and has copper fingers all around the vault door to help with shielding.

Anyway, back to the issues:

2 – Bypass capacitors in filters, at higher frequencies move towards inductive, reducing or eliminating their effect.

3 – Series inductors in filters can be bypassed by higher energy capacitively coupling around it or radiating around it.

4 – Earth’s magnetic field effect on focusing the effect

Regarding aircraft-borne radar – they are quite low power. A search radar in the maritime patrol aircraft I once crewed had only about 1KW of average energy, and about 160kW of peak power – in other words, it was almost exactly a microwave oven, except it sent the energy out. They don’t operate a couple of feet from consumer and industrial electronics either – they, unlike the EMP effect, do suffer from 1 over r-squared.

If your calculations used the 1/r-squared law, they are wrong. The electric field pulse is generated over a wide area of the upper atmosphere, putting the ground beneath it in the near-field, resulting in effectively zero loss with distance.

Four problems with your analysis:
1) Higher frequencies can get through smaller gaps in shields than lower frequencies. A lot of equipment is shielded for lower frequencies. Aircraft weather radar operates at quite low energy ( US government report(Link) on the phenomenon. It does the calculations you want and arrives at far more alarming (but correct) conclusions than you do. It explains why.

BTW, the US govt (at Sandia Labs in Albuquerque) conducts EMP testing of all sorts of things using accurately simulated EMP. They actually know, not only from physics, but also from experiment, that EMP is an enormous problem.

“Forstchen’s work is garbage, as I explain in the articles linked above”

Forstchen is writing dramatic fiction. Since he is not well trained in the physical sciences, he makes the sorts of mistakes that you ridicule, which are irrelevant to the effects he describes, since he took them from people skilled in the field (see report above). He is mostly correct – he hypothesizes two or three HEMP bursts over the US (I think two, not sure) along with attacks on countries that might come to the aid of the US or provide replacement parts. Forster exaggerates the effect (100% disabling of all micro-electronics based equipment, primarily). But, a significant EMP attack against the US would kill a lot of people, and the death toll could reach into the millions, as our just-in-time supply chain for food, fuel and pharmaceuticals could be disabled for (potentially) months.

The power grid problems are also very significant, because extremely large custom-made pieces of equipment (such as transformers and generators) are destroyed. These cannot be replaced for quite a few months, especially if a lot are lost at once. Major portions of the grid will be out for months.

First of all, you seem to be ignoring the amplifying effect of the earth’s magnetic field, which was described fairly well in the Wikipedia article Ben linked about. It’s not simply the gamma radiation initially emitted by the nuclear device which is so destructive, it’s the cascading and cumulative effect of the three separate phases of the pulse.

You also seem to make the assumption that the EMP pulse will affect structures on the planet’s surface in some qross physical way (c.f. your comment “I am not sure how the good professor ever thought that something that fried all electronics, even the shielded ones in a car or an electrical substation 1500 miles away, wouldn’t hurt at least some of the people 300 miles below, who were receiving 25 times the power.”). But it isn’t that the pulse “fries” all electronics, only the extremely sensitive ones upon which nearly all of our technology now relies. We know it doesn’t much effect vacuum tubes or older, more robust, forms of technology. Why do you think it would be felt by a human simply because it destroyed a transistor? An impact which squashed a gnat wouldn’t even be felt by a human. Besides, my understanding is that gamma radiation is imperceptible, but nonetheless fatal.

My opinion isn’t worth much; I’m not a scientist or engineer. But I think the opinion of the US EMP Commission is worthy of some respect. There are some highly qualified people on that commission, and I’m sure that their staff was equally capable. Their 2004 Report was full of phrases such as “catastrophic impact”, “unprecedented cascading failures of our major infrastructures”, and “damage that could reach large-scale, long-term levels.” Their more detailed follow-up report in 2008 was equally chilling. Frankly, I give their analysis and conclusions much more credence than your “scratch calculations”.

Not only are higher frequencies easier to block, but 1 GHz is not that great. An aircraft weather radar tends to work at around 9 GHz, and while they should be turned off after landing they are occasionally left on. The power density from these close by is far higher than the likely average power from an EMP from even a large weapon over the USA, yet they don’t actually damage nearby electronics, except perhaps the most vulnerable.

Likewise any lower-frequency pulse would have to have far more energy than any likely source to do the kind of damage you suggest.

Forstchen’s work is garbage, as I explain in the articles linked above.

http://my-own-doubts.blogspot.com/search/label/EMP

If we can get our nukes off to wipe out the little rat who runs Iran, that’s the only thing that matters in the end. Thus we need to make them aware of what war will do to their bid to be the ruler of the muslim world.

The last airburst nuclear tests were in the mid-1960s, right? At that time, virtually all electronic systems and gadgets were vacuum-tube-based. The great transistor revolution didn’t happen until a few years later. Aren’t vacuum tubes MUCH more resistant to EMP than transistor circuits?

And a question: what would be the effect of an EMP burst on light-based circuits such as fiber optics? What would be the effect on flash memory?