I've been following this thread for a while now, and finally couldn't let this nonsense go unanswered.
First, most of what has been said in this thread is effectively the output of the south end of a north-bound bull. At least one of you claims to be an expert, yetmdoesn't know what in the hell he's talking about, and when presented with the evidence and a formal national academies report, has the balls to say that it agrees with his head-in-the sand opinion.
Second, there are several posts saying "why bother?" EMPs will come from nukes, and nukes aren't survivable. mzmadmike posted the Carrington event as an example of why one should bother preparing for an EMP. Of course he got attacked saying that CMEs are not EMPS and can't do the damage of an EMP. Wrong, again. A flare or CME *especially* during a solar minimum, would wipe out most if not all of the world's electrical infrastructure. It wouldn't matter if your car ran if there's no way to get gasoline, or if your laptop worked with no internet.
Third, the idea that a device has to have an antenna to be affected by EMP is crap. If that is true, why is everyone so worried about electronics? Does a laptop CPU *really* have a long antenna? No.
Fourth, you are all arguing semantics over whether a nuke or flare strong enough to fry electronics won't just fry *you* - therefore it's not worth preparing for. Again, bull crap.
Get your collective heads out of Wikipedia - which is 1/2 truth, 1/2 lies, and 1/2 the kind of uninformed guesswork that this thread has been perpetuating - and go read the primary sources. They are available on the internet if you go looking for them. If you don't understand them, find someone who *does*! Stop guessing and mutually stroking each other when someone posts something you like!
Now, the facts, from someone that knows and works with physics and electronics every day and has to deal with the consequences of EM interference, pulses and induced currents...
EMPs have 3 parts - E1, E2, E3.
E1 is the effect caused by gamma rays striking atmospheric molecules and releasing electrons. This is the nuke-derived *pulse*, and it will fry unprotected electronics.
E2 is the static electric discharge conducted through the air to grounded conductors.
E3 is the geomagnetic pulse and can come from a nuke or solar event. Flares, CMEs and nukes *push* against the Earth's magnetic field and the resulting wave and rebound induces a current in long conductors.
Antennas: Antennas are important in all three phases: they can be affected by the electron pulse, ground the static discharge, or received an induced current. Grounding the antenna prior to the electronics will protect against E2, but not E3. An antenna is not really affected by E1 - nor is lack of an antenna protection against E1.
Lack of antenna protecting electronics: Bullcrap. The electron shower from the gamma ray pulse affects all electrical conductors. The ones that develop more heat than they can dissipate will melt. In common terms that means long wires and antennas develop large currents, but the microns thick wiring in silicon chips can *not* dissipate more than a few calories worth of heat, so they melt. The key is not *length* of the conductor, but a combination of length, thickness, and the melting point of the conductor.
Faraday cages: (1) Faraday cages *must* be grounded, and they must be made of a good conductor with holes no larger than the wavelength of the radiation in the pulse. (2) Faraday cages don't protect against E3, and their E2 protection is only as good as the ground conductor. In practical terms an effective faraday cage can be made from mesh with holes no larger than 1/2 centimeter and block all radio and microwave radiation. Cars are not good faraday cages - that huge windshield is not exactly <1/2 centimeter. Aluminum is okay for faraday cages, but foil is not very effective - the conductor is too *thin*. Steel and copper *wire* mesh are better. There is a reason why commercial shielding and grounding uses braided wire and mesh for shielding and again, to be effective, a Faraday cage must be *grounded*.
Nukes and EMP: It's true that the nuke needs to be above the densest part of the atmosphere. About 100 miles will do. EMP is not strictly line of sight, it follows the Earth's magnetic force lines. Guess what - North America is a hell of a lot more susceptible to EMP than anywhere else- mostly because of the magnetic field emanating from the magenetic North Pole (which, duh, is in North America). So a 100 kt nuke over Canada can EMP a large portion of the US. Sorry, guys, but that's a scenario in which EMP is a very real threat *without* nuclear war.
CMEs, Solar flares and EMP: A solar flare or corona mass ejection (CME) releases high energy particles at 0.25-1.0% light speed. Astronomers will see the flare/CME, and the effects will show up around 800 hrs later. The impact of these particles with the Earths magnetosphere will (1) *push* against the geomagnetic field [E3], and (2) release additional gamma rays in the extreme upper atmosphere, resulting in *some* gammas making their way to the lower atmosphere to cause E1 - just not as severe as a nuke. The E3, however, will be severe, as in the 1859 Carrington Event. And it's not just long power cables that will be affected! *Any* long conductors will be charged. The power lines from generating plant to transformer may be protected, but what about the *plumbing*? There are also geological features that carry charges, the North American high plains are full of them - also nickel, iron, bauxite, gold, silver veins and deposits! The geomagnetic pulse may be relatively slow from an EM standpoint (effectively DC, someone said) but it is nonetheless an electrical charge, and it is *not* the instantaneous pulse, but the capacitive charging and discharging that produces the oscillation that results in damaging voltage. Most electronic devices such as diodes and transistors conduct current only in one direction and block flow in the opposite direction, but each also has a failure point - supply enough charge and they fail and conduct in both directions - a short circuit. The key is charge density, and the specific failure is dependent on how much charge, and how much conductor, be it 12 micron traces in your laptop or inch-thick 440 V power lines.
So. Here's the facts. Do what you wish with the knowledge, but at least stop standing around in a circle stroking each other with conjecture and half-truths.
s2la - The Speaker to Lab Animals
Zombie Neuroscience Specialist