One of the longest-sought, most keenly anticipated high-tech weapons of the past century - namely, the dreaded circuitry-frying electromagnetic pulse bomb - seems to have had its schedule moved forward.

The electromagnetic pulse (EMP, aka High Power Microwave or HPM) weapon has long been theorised upon, ever since it was found that a nuclear explosion would produce such effects at the tail end of World War II. People have speculated ever since that one might use EMP strikes - produced either by high-airbursting nukes, or perhaps by conventional explosives-pumped systems of some kind - for offensive purposes.

The EMP/HPM effect would be mainly useful for attacking electrical systems, though like any non- or less-lethal weapons technology it has acquired the reputation (among the ignorant, anyway) of being almost more dangerous to humans than an ordinary bomb would be.

But so far the only reliable way to produce a decent EMP has been to set off a nuke, and the game hasn't been seen as worth the atomic candle. The US military, seeking ways to addle enemy air defences and communications, has repeatedly tried to develop conventional EMP/HPM warheads powered by chemical explosives, but thus far without much luck.

Hints in a presentation given by a US air force official last year suggested that the American forces didn't see a viable pulse bomb coming into production any sooner than 2012, perhaps once some basic research had been carried out.

Now, however, another presentation by the US general in charge of the Air Armament Center has suggested that an HPM weapon "packaged in inventory munitions mold line" - ie, it is a bomb - is already at the stage of "industry technology assessment" and a technology demonstrator could be built next year. (Here, in pdf - page 30.) The presentation was flagged up by Flight International reporter Stephen Trimble at his DEW Line blog.

Of course, the US forces have thought they would have a working pulse bomb within a year or two for the last couple of decades at least, so there may not be any immediate need to start wrapping all your kit in tinfoil Faraday cages just yet. But this shorter timescale does seem to make some sense out of the Pentagon's ongoing efforts to harden military radars and so on - which, if they're to work, can't be kept inside Faraday shielding - against pulse strikes.

There are those in the state of Maryland who aren't waiting for the US military to crack the problems, though.

"A rogue state or terrorist organization could easily acquire nuclear material for a smaller weapon for $20m," says Charles Manto, president of Instant Access Networks corp.

"That weapon could be fitted onto a Scud missile for as little as $100,000, fired and detonated 80 miles into the air and affect the entire US east coast," he adds.

Manto has just scored some state funding to prep the Maryland power grid for the inevitable terrorist Scud nuke pulse strike. He reckons to do this using "patent-pending shielding technology that encloses a room or similar structure and protects it from EMP events ... [the] shielding, which includes layers of steel and aluminum, is up to 70 per cent lighter than materials traditionally used ... This enables EMP-safe rooms to be portable."

In addition to the portable tinfoil rooms, the plan is to establish pulse-proof "microgrids" powered by renewable energy sources such as windmills.

"A residential-scale wind turbine" will be pulse-hardened and used to start with, apparently. (That is, a rooftop windmill of the type which is about as much use as a chocolate teapot).

We can't help feeling that the microgrid/tin-room/rooftop-windmill plan doesn't go far enough. Surely some kind of wearable rig would also be in order, featuring the traditional pulse-proof hat coupled with an on-head wind turbine providing reliable power for one's personal electronics. ®