[max americana]

Read about Faraday cages and how to build them.An old microwave oven is an excellent Faraday cage.

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Using the AM/FM radio test, it was found that both Mylar bags and microwave ovens were not good Faraday cages. Both of these failed inside my home. They simply did not work well at all.

http://thesurvivalmom.com/why-and-how-to-protect-your-gear-from-emp/

[blackdog]

There is a company called Insul-Fab. They make a metalized sheet of plastic which is laminated. It comes in rolls like wallpaper. You overlap the edges and apply it like wallpaper to metal studs. The studs you apply a big copper fender washer at each screw to attach to the metal. You run the stuff floor and ceiling too, making sure to overlap the conductive side to each. This makes a Tempest or shielded room good to about 80db. You feed the room with an isolation transformer and ground the whole thing to a grounding rod ten feet into the ground. Don't forget a steel door with RFI gasketing and EMI / RFI attenuating vents for the air supply.

The CIA and NSA build this into their offices. They put sheet rock right over top so it looks like an office. A company called DonTek in Suburban Philadelphis makes a mesh which is stainless steel, silver plated, and carbon black coated that sandwiched between two layers of glass for the windows. It will also stop EMP, EMI, RFI problems.

I used to buid shielded rooms.

[higgmeister]

Interesting about the AM/FM radio test because I have seen it in action in an MCI facility. We had experienced sporadic crosstalk possibly as the result of grounding problems. A venerated old Korean Engineer from Richardson, TX came to the site to check our grounding. He pulled an old hand held transistor radio from has pocket, moved the tuner all the way as far as it would go and turned the volume up. He used it like a Geiger counter sweeping up and down all around the room. He located two ungrounded raised floor tile pedestals that were radiating noise. He suspected the noise was interference from an ATC Radar facility a few hundred yards away. Amazing to watch it.