radio shielding

I am curious as to what a metal building will do with regard to shielding high frequency radio signals. These radio signals may be from 500 Mhz up to possibly 1 Ghz signals and I'm curious if anyone knows the effect of protecting yourself from high frequency radio signals under certain conditions. I deal with radio signals a consider amount of the time and am considering investing in a metal roof and metal siding on a building because of a high radio environment. I've considered the effect of grounding the building although I'd like to know if anyone knows how effective of a shield that may make? Gary M.

Reply to
Gary Mikulich
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A really good screen room is hard to make, but solid material isn't necessary. Better conductors make better shields, but a dollar's worth of iron is a better shield than a dollar's worth of copper. Openings -- including slits -- larger than about a tenth of a wavelength -- make the shields ineffective. Doors are hard to seal at frequencies that interest you.

Jerry

Reply to
Jerry Avins

You don't need to ground the building. You don't need to join the metal panels together ( though that's best ) but you do at least need to overlap flat panels by a reasonable amount so they are in effect shorted together capacitavely at HF. Mesh of sufficiently small aperture ( lot less than the target wavelength ) will attenuate HF a lot, or use wave-guide beyond-cutoff pipe arrays to let in air and a little light.

Basically you want a Faraday cage, which is an equipotential surface (i.e. a conductor ) with no gaps.

The really tricky stuff is LF.

Andy.

Reply to
Andy

Hello Jerry,

Not really. At frequencies that Gary needs (>500MHz) a nice big overlap should do. For lower frequencies they have finger stock but I always avoid touching it. If it's copper beryllium it may not be such a good idea to touch it and then eat a sandwich as the oxide of it is pretty toxic.

Regards, Joerg

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Reply to
Joerg

It's hard to make an overlap without a lateral gap. A narrow gap can act like a waveguide beyond cutoff, but it can also become a slot antenna. Choke joints can be very effective over a narrow frequency range.

Beryllium is toxic, especially when compounds are inhaled. Once alloyed, the result is about as inert as any metal can be. Like the mercury in amalgam fillings, it is so tightly bound as to be innocuous.

Jerry

Reply to
Jerry Avins

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