The Tin foil hat acts as a crude 1/2 and 1/4 wave cavity (the diameter of the tin foil hat) amplifing the Electro Magnetic waves from Government Radio transmission. Best stick to some aviation 'stealth' RAM principles - A motor cycle helmet covered with glued on Ferrite disks works the best. (best to glue them on the inside of the motorcycle helemt otherwise folks will think you look a bit strange)

http://parts.digikey.com/1/parts/672514-ferrite-emi-disc-16-51mmx1-27mm-mm0650-100.html