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Re: MIT study on aluminum foil hats

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gilber34 <fafa@invalid.com> wrote:
> On 11/15/2015 8:33 PM, jimp@specsol.spam.sux.com wrote:
> 
>>> skin effect is only one part of the problem, re-radiation from the other
>>> side is another, a reason most shield rooms have two screens attached at
>>> a single point between them. and also lack of sufficient attenuation in
>>> material.  Gov switched from copper to galvanized steel sheet for many
>>> of their SCIFs, much cheaper, + better attenuation.  Need to knock it
>>> down by 90 to 150 Db
>>
>> Re-radiation from the other side of a closed, solid conductor is impossible
>> for practical sheet metal of any kind.
> 
> 
> True, if the solid conductor is thicker than skin depth, and has some 
> Iron content to attenuate down to 1KHz.   But the seams, doors can be a 
> challange, etc.

No, it does not have to have iron content.

> It is a matter of how much attenuation you want, 20 Db or 150 Db
> more material, more layers, more attenuation. (easier as you go up in 
> frequency)

Layers are needed because of leaks in screen and things like door seals.

It is far cheaper to use multilayer screens than it would be to use
solid sheet metal.

> Try cutting off a DC magnetic field from a PMT tube

DC is not RF and a totally separate issue.


-- 
Jim Pennino

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MIT study on aluminum foil hats Sam Wormley <swormley1@gmail.com> - 2015-11-15 14:59 -0600
  Re: MIT study on aluminum foil hats jimp@specsol.spam.sux.com - 2015-11-15 21:05 +0000
    Re: MIT study on aluminum foil hats "Ross A. Finlayson" <ross.finlayson@gmail.com> - 2015-11-15 13:24 -0800
      Re: MIT study on aluminum foil hats "Ross A. Finlayson" <ross.finlayson@gmail.com> - 2015-11-15 13:26 -0800
      Re: MIT study on aluminum foil hats jimp@specsol.spam.sux.com - 2015-11-15 21:58 +0000
  Re: MIT study on aluminum foil hats Fabian Russell <root@localhost.localdomain> - 2015-11-15 21:37 +0000
    Re: MIT study on aluminum foil hats jimp@specsol.spam.sux.com - 2015-11-15 22:04 +0000
      Re: MIT study on aluminum foil hats Fabian Russell <root@localhost.localdomain> - 2015-11-15 23:00 +0000
        Re: MIT study on aluminum foil hats jimp@specsol.spam.sux.com - 2015-11-15 23:05 +0000
  Re: MIT study on aluminum foil hats gilber34 <fafa@invalid.com> - 2015-11-15 16:06 -0600
    Re: MIT study on aluminum foil hats jimp@specsol.spam.sux.com - 2015-11-15 22:57 +0000
      Re: MIT study on aluminum foil hats gilber34 <fafa@invalid.com> - 2015-11-15 19:51 -0600
        Re: MIT study on aluminum foil hats jimp@specsol.spam.sux.com - 2015-11-16 02:33 +0000
          Re: MIT study on aluminum foil hats gilber34 <fafa@invalid.com> - 2015-11-16 10:12 -0600
            Re: MIT study on aluminum foil hats "nuny@bid.nes" <Alien8752@gmail.com> - 2015-11-16 09:28 -0800
            Re: MIT study on aluminum foil hats benj <none@gmail.com> - 2015-11-16 12:52 -0500
              Re: MIT study on aluminum foil hats jimp@specsol.spam.sux.com - 2015-11-16 19:43 +0000
                Re: MIT study on aluminum foil hats benj <none@gmail.com> - 2015-11-16 21:55 -0500
                Re: MIT study on aluminum foil hats gilber34 <fafa@invalid.com> - 2015-11-16 23:04 -0600
            Re: MIT study on aluminum foil hats jimp@specsol.spam.sux.com - 2015-11-16 19:39 +0000
  Re: MIT study on aluminum foil hats HVAC <mr.hvac@gmail.com> - 2015-11-16 03:24 -0800
    Re: MIT study on aluminum foil hats HVAC <mr.hvac@gmail.com> - 2015-11-16 03:26 -0800
      Re: MIT study on aluminum foil hats benj <none@gmail.com> - 2015-11-16 12:42 -0500
    Re: MIT study on aluminum foil hats benj <none@gmail.com> - 2015-11-16 12:40 -0500

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