Re: [TCML] Faraday Cage Safety

[dave pierson <dave_p@xxxxxxxxxxx>]

> I've got some questions I was hoping you or someone else could answer
> about Faraday cages:
> 
> What would be a safe mesh size to catch streamers from entering the
> cage?
   Leaving?
   Any reasonable _mesh_ from 1.5" 'chicken wire on down to
   window screen.  Or an array of bars.

> More important would be, what mesh size should one use to have a
> Faraday cage that's effective to keep interference within?
   Keeping RFI/EMI inside also depends on handling all
   wire penetrations correctly:  filters 'in' the
   'wall', 'bonded' to the wall.  This becomes more
   critical in dealing with the VHF range strays, rather
   than the 20/50/100KHz/whatever 'fundamental'.

   Planning for some debug/test/rebuild time is
   desirable.. 

> I only presume it has got something to to with the wavelength
> of the emitting device?
    Yep.  The rule of thumb i was familiar with was openings
    to be smaller than 1/10 the wavelength.  This is simple
    at the '50 KHz end', may take some attention at the VHF
    stray end.  A subtlety is that this measure applies to
    the single longest dimension of an opening: picture
    a solid copper room, with a solid copper door.  close
    the door and its still a 6 ft opening, unless some
    bonding/finger stock is provided.  (OK: likely
    not relevant to most cases here.) 

    best
     dwp 
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