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Re: Shielded rooms, faraday cages, etc.

Completely surrounding something with multiple layers of aluminum foil with
no gaps WILL do a fairly good job shielding.  My earlier back of the
envelope calculation worked out to a microwave oven only needed 30 or so dB
of attenuation to meet safety requirements, so as far as shielding goes,
the microwave is terrible.

Completely enclosing something in Al foil should give you around 60 dB or
better (depending on how clean the foil is, how good a contact between
layers, etc.)

The saving grace for tesla coils is that they are terrible antennas and
don't actually radiate that much power.  40 dB of attenuation on your walls
from chicken wire or screening will probably reduce the TC produced noise
to less than the background noise floor. I'd use a AM radio as a detector. 
Hook up an ac voltmeter to the speaker/earphone output, so you can get some
quantitative measurements. Your measurements will get somewhat distorted 
by the AGC in the receiver though.  One way to back that out is to tune
around and find a commercial station that shows up at the same power as
your TC does (as measured by the volt meter).  Then, knowing the power of
the commercial station, and its distance and antenna pattern, you can
figure out how much power you've got at your location.

----------
> From: Tesla List <tesla-at-pupman-dot-com>
> To: tesla-at-pupman-dot-com
> Subject: Re: Shielded rooms, faraday cages, etc.
> Date: Saturday, April 15, 2000 12:32 AM
> 
> Original Poster: "Ruud de Graaf" <rdegraaf-at-daxis.nl> 
> 
> Hi Terri, Jim, All,
> 
> How would you explain the fact that surrounding the cell phone with Al
foil
> completely will do the trick? (try it out, it's probably in the kitchen,
> watch the wife though) Without the Al shielding I had a S4 signal.
> 
> I'am pretty convinsed that Cu would be better to use than Al for
shielding,
> but how is it to explain that the copper ball does not shield enough? I
> didn't have massive copper enough, but I tried very narrow copper mess
> (copper 'rings' found in microwave tubes)without any result! The signal
> stay'd S4. Was the copper ball massive, Terry?
> 
> Maybe my phone is not that sensitive as Jim suggests. I have a Nokia 3110
> for about three years now.
> 
> I'am very glad with the answers, because I had already bought chicken
mess
> to use as RF shielding in my garage and I was afraid it would'nt help a
bit.
> Well even when it does not work out for the RF radiation, it shure will
keep
> the HV ware it belongs...
> 
> Greetings from MOTting Holland,
> 
> Ruud
> 
> 
>