http://www.techworld.com/mobility/features...amp;pagtype=allThis is an interesting article about companies wanting to block wireless access into and out of their facilities by means of a Faraday Cage:
QUOTE
A Faraday cage is an enclosure designed to exclude electromagnetic fields. It is an application of Gauss's law, one of Maxwell's equations. Gauss's law describes the distribution of electrical charge on a conducting form, such as a sphere, a plane, a torus, etc. Intuitively, since like charges repel each other, charge will "migrate" to the surface of the conducting form. The application is named after physicist Michael Faraday, who built the first Faraday cage in 1836, to demonstrate his finding.
--from the Wikipedia Article about Faraday Cages
Years ago I used to spend part of each day in a Faraday Cage built of brass screen door screen when I was working on building radios for Bendix-King.