What started strictly as "a desire to play with some expensive equipment" ended with surprising results, says lead study author Ali Rahimi, a recent graduate of MIT's doctoral program in electrical engineering and computer science. Overall, the foil effectively weakened radio waves by up to 10 decibels over most of the frequency spectrum (there were no significant differences among helmet shapes). But at 1.2 and 2.6 GHz-which fall within the band reserved for government satellites, GPS systems and mobile phone corporations-passage through the foil amplified these waves by 20 to 30 decibels. Although Rahimi doesn't know why the foil increases only those frequencies-antenna design is a "black art," he says-the implications of the research were clear. "It requires no stretch of the imagination to conclude that the current helmet craze is likely to have been propagated by the
Government, possibly with the involvement of the FCC," the students sagely declared. "If there are radio waves involved in reading minds, aluminum hats aren't an effective way to counteract them."