Re: Faraday Cage

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "davep by way of Terry Fritz <twftesla-at-qwest-dot-net>" <davep-at-quik-dot-com>


>Regarding all of this cage design, about what frequency

>does RF become highly directional (like microwaves)?

         As noted, depends on the size of the opening
         (or reflector) measured in wavelengths.
         Longer wavelengths 'refract' around obstacles
         and appear less directional
         (this was one thing that fooled Tesla:
         What he thought was 'new wave' flowing
         THRU hills, was LF waves refracting around them.
         VHF (called 'Hertzian', then, were known NOT
         to refract so well.)

>Would coving the floor be relevant?

         If bonded to the cage wall, will prevent
         leaks at the floor wall join.  To the
         extent that the _main_ wavelengths are long,
         I'd expect the UNbonded slot to keep the
         _main_ signal inside.  Where the bonding
         is helpful/critical is keeping in the
         VHF strays from lead resonances on the
         wiring.

>Will the RF simply radiate toward the floor and the earth underneath, 
>without curving upwards into the house

>(or horizontally and out into the neighborhood)?
         With or without the screen on the floor?

         Arguably, without the screen on the floor
         the main freq will get 'lost' in the soil, eaten
         up by the soils resistivity.
         With the screen, main freq should stay inside
         the cage (at least as far as the _floor_
         _screen is concerned.  Might escape elsewhere.
===================================================
Related:
I would concur (kept forgetting to state) that running
a coil has risks, even with 'faraday cage'.  Notably,
I know Just How Hard it is to debug one.

And the ventilation risks are important also.


         best
         dwp

...the net of a million lies...
         Vernor Vinge
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         -me