I am confused by that. One guy told me that he puts aluminium foil on his modem to receive the Internet better. Another guy told me that aluminium stops all kind of rays. What is correct?to improve WiFi signals. But it just acts like a reflector. In other words it increases the signal in one direction and reduces it in another. Another guy told me that aluminium stops all kind of rays. It reflects some kinds of waves. It does not reflect or stop high energy stuff like X-rays and gamma rays.Actually MIT did an experiment using tinfoil hats of various types plus a scalar network analyzer. They found that at certain frequencies, a tinfoil hat actually INCREASES the amount of radiation. Furthermore, these frequencies have been allocated by the FCC for government use. It all depends in the gaps in the foil, the shape, and the exact way in which it is joined.BOTH ARE CORRECT.... COVER THE WHOLE WIRELESS MODEM WITH ALUMINUM FOIL AND GROUND IT SHALL BLOCK ALL THE WIRELESS SIGNAL. CONNECT A SMALL PIECE FOIL TO THE WIRELESS MODEM ANTENNA MIGHT INCREASE THE RANGE A BIT SOME TIME BUT USUALLY NOT WORKING WELL.You can use
aluminum foil to build a reflector to make a Wi-Fi router directional, and increase its range. You can also use it for electromagnetic shielding. Design matters.If you totally enclose and electronic device in
aluminum foil no radiated electric fields will get through it, because it is a Faraday cage.Other related question