by government, these bands are at the hands of multinational corporations.   http://people.csail.mit.edu/rahimi/helmet/   For half-millimeter-thick tin-foil, radiation above about 20 kHz (i.e., including both AM and FM bands ) would be partially blocked. http://en.wikipedia.org/wiki/Tin-foil_hat   Blocking transmission A Faraday cage or Faraday shield is an enclosure formed by conducting material