To make strong microwaves, you need a lot of electricity, usually from a bulky generator. Instead the team packed small explosives into a five-foot-long, six-inch-wide tube. The detonation produces a burst of electrons, which power a microwave tube—similiar to the type in a microwave oven—that radiates microwaves. An antenna zaps those at a target, where they can cause a circuit-frying current surge in electronics. The explosion destroys the device, and although the U.S. Army funded the work for "educational purposes," it doesn't take much imagination to think of uses for a one-shot, missile-shaped electronics buster,says James Benford, a high-power-microwave expert at Microwave Sciences in California.