The longstanding mythology around the use of tin foil hats to block the government and extraterrestrials from reading or controlling a person’s thoughts using radio waves dates back to the late 1920s. The scientific logic is that the foil helmets act as a Faraday cage, an enclosure comprised of a conducting material that prevents external electrostatic charges and electromagnetic radiation from entering by distributing them around the exterior of the cage. However, the typical foil hat does not fully enclose a person’s head as an effective Faraday cage would and is ineffective at blocking radio frequency electromagnetic radiation.
In 2005, a group of MIT students tested the effectiveness of foil helmets at blocking various radio frequencies by constructing three different helmet designs out of layers of aluminum foil. Using a radio frequency signal generator and a receiver antenna placed on various parts of their subjects heads, the students examined the strength of the transmissions. The students discovered that though the helmets shielded the wearers from the majority of tested radio waves, they amplified certain frequencies, including those in the 2.6 Ghz—allocated for mobile communications and broadcast satellites—and those in the 1.2 Ghz—allocated for aeronautical radionavigation—bands.
