aluminum foil on the walls

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On Wed, 15 Sep 1999 06:59:07 -0700 (PDT) Brian D Williams <talon57@well.com> writes:
>
> Unless it was properly grounded (Faraday shield) it would not form
> an effective shield against "radio waves" or microwaves, nor would
> it be an effective anti-Tempest defense. (Van Eck Radiation)
>
>
> Brian
>

If a 10 foot by 10 foot aluminum sheet were ungrounded and hit facewise with 1 MHz (300 meter) EM radiation, the EM field would not be attenuated much at all, even right next to the sheet, in the center, in the lee (shadow). This is because the sheet is much smaller than the wavelength, and ungrounded.

But if a 10 foot by 10 foot aluminum sheet were ungrounded and hit facewise with 1 GHz (0.3 meter) EM radiation, the EM field would be much attenuated in the lee of the sheet, for a receiver close to the sheet and near the center of the sheet. This is because the sheet is much larger than the wavelength, and highly conductive.

Ron Kean

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