The last time I looked at this all the studies were done in the era of short wave radio. The generation mechanism, as EMPcover cites, is based on a broad ionospheric phenomenon which is ideal for coupling to the power grid but does not seem like it can generate dangerous modes at frequencies our portable electronics uses. Right? Most devices with stubby antennas, centimeter scale frequency bands, and packages designed (for other reasons) to shield the circuits and with anti-static shunts on the pins, seems like most of our mobile devices would survive. And all long lines are optical. We might be able to harden enough of the supporting towers so at least the information networks limp along.
Of course, wiping out the power grid remains a major problem. How fast that comes up depends on whether we simply trip circuit breakers or actually destroy equipment. EMP events from major solar flares have done that too, it does not need to be man-made. Indeed a solar event of the scale of the largest known (in the 1800s, it damaged telegraph lines at that time) would probably pack far more power and damage than a nuclear pulse.
Any US enemey (I can think of some) with the capability of creating an EMP attack using a nuclear weapon is far more likely to import the nuclear device in a crate marked "spare parts for tractors" and detonate it at ground level. Why knock out an American citizens' iPad when you can knock out the citizen at the same time? It's not communist USSR you are up against, you know.
"So here’s a thought; instead of spending billions making and stockpiling weaponry, why do governments not spend a fraction of that amount to defensively protect their most important resource –electricity—from disaster?"
Because it's not an either/or matter? If you had perfect EMP protection and nothing else, would that make you any safer?
Actually, one good way to protect against EMP could be to use old-fashioned tube electronics, at least for your backup, mostly manual controls. But also devices that can shunt very high voltages for short periods of time in the power supply of electronic devices, such as metal oxide varistors (MOV).
DoD specs usually do require protection against high voltage pulses, although I'm not sure whether these specs are always adequate for EMP protection.
Wow, thanks for all that additional info EMPCover, that adds a lot and gives our readers much to chew over. I think it is an issue that needs to be brought to the fore of public consciousness, and that governments should be taking measures to protect against it, since it is a known and credible threat.
You are right that it does take a large group to push for significant funding. The EE community is just the right group to lead that charge.
It is important for EEs to understand the threat. There is a lot of misinformation and general disbelief in the media.
There are also things that EE can do as individuals, both to protect your family and your business.
The first thing we always recommend is to build a basic three-day emergency kit, as recommended by FEMA and the Red Cross. You should have one at home... and also be sure your business has a kit. How will your staff survive if they are stuck at work for two days without power? Will your building have water if the pumps shut off?
Second, since you are reading an EE article, you probably need to figure out how to protect backup electronics. Our site has a lot more information on that.
EMP pulses don't directly follow the inverse-square law because they are not point-radiation sources.
Most of the EM energy is not generated at the blast location. An EMP basically turns the atmosphere into a huge phased-array antenna.
The most important energy is generated two ways. First, the E1 pulse is generated when the explosion's gamma rays hit the upper atmosphere. The Compton effect creates a current that radiates generally downward. The frequency range is generally 100 kHZ to 1 GHz.
Second is the E3 pulse. The fireball from the high-altitude blast deforms the earth's magnetic sphere asymmetrically. This 'heaving' generates lower frequency EM which couples with transmission wires. The energy lasts from 10 seconds to up to 3 to 4 minutes.
You are right, however, that some experts overhype the issue. The most likely attack is using a bomb that can only produce regional or multi-regional damage. (See our site's EMP simulator for graphics.)
The worry we have, however, is that the 'over-hyping' comes from specialists who have the clearances to see the classified information.
These experts say that there are credible designs for super-EMP bombs. They say that these could be much smaller nuclear bombs, but specifically designed for EMP.
So these worried experts are talking about worst-case scenarios. The more-likely attack would be regional.
Of course, most people dismissed warnings that an airplane could collapse buildings like the twin towers. They also thought that Pearl Harbor couldn't be attacked with torpedoes because it was too shallow.
The experts say that these specialized bombs could cause a coast-to-coast blackout.
(Of course, you could also do the same with a couple of multi-megaton warheads. That size blast, however, would likely kick off a global thermonuclear war.)
Blog Doing Math in FPGAs Tom Burke 23 comments For a recent project, I explored doing "real" (that is, non-integer) math on a Spartan 3 FPGA. FPGAs, by their nature, do integer math. That is, there's no floating-point ...