Now, whats so hard about blocking a cell phone signal completely?
Let’s say you don’t own a cellphone and want to shield your house completely from external signals. Or maybe you have a secure area (such as a hospital, data center, prison, or movie theater) and you want to prevent incoming or outgoing calls. There are many shielding materials you can put on walls and windows. But there is a big problem: cellphones can operate very nicely with only a very small fraction (less than 1 millionth) of a normal signal. 1- Therefore your shielding materials must provide very high attenuation levels. Typically, 80 to 100 dB attenuation materials are required. 2- You must control leakage point VERY carefully. Gaps under doors, joints between shield sections, and even pinholes from sewing shielding material can permit these high frequency signals to penetrate. You need to create a “complete” enclosure. Any part that is not shielded is a leakage point. A small pouch is not that difficult to make with the proper material. Shielding a whole house, or even a whole
