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Re: MIT study on aluminum foil hats

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gilber34 <fafa@invalid.com> wrote:
> On 11/15/2015 4:57 PM, jimp@specsol.spam.sux.com wrote:
>> gilber34 <fafa@invalid.com> wrote:
>>> On 11/15/2015 2:59 PM, Sam Wormley wrote:
>>>> MIT study on aluminum foil hats
>>>>> http://boingboing.net/2005/11/11/mit-study-on-aluminu.html
>>>>
>>>>
>>>>> Earlier this year, MIT engineers conducted an empirical study on the
>>>>> efficacy of aluminum foil helmets to block mind control rays. They've
>>>>> published the detailed results of their experiments online. From the
>>>>> abstract:
>>>>
>>>
>>>>
>>>
>>>
>>> Aluminum does not stop low frequency waves, below 2Mhz, at all.  Nor Copper.
>>>
>>> Need Iron content for that.
>>
>> Not true; RF is RF.
>>
>> Look up "skin effect" for why foil may not be the answer for low frequency.
>>
>>
> 
> 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.

Screens always have leakage, which is quite different than re-radiation.

> 
> http://www.rfcafe.com/references/electrical/skin-depth.htm
> 
> note it depends upon permeability, of which Iron is far higher than Al.

Note it actually depends on the resistivity, frequency, magnetic
permeability, and the permittivity.

> material Relative Permeability μ/μ0 - Skin depth (0.1Mhz)
> 
> AL               1                        259.0 um
> Fe              500                       22.2 um

If that is supposed to be skin depth, it is meaningless without frequency.

 
 

-- 
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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