[TowerTalk] Faraday Cage

[Martin Ewing AA6E]

> However, remember the Faraday cage is an electrostatic shield, not a 
> magnetic one. How well would it protect from the field produced from a 
> few thousand (or more) amps?  I have no idea.
>
> 73
>
> Roger (K8RI) 
True, when considering *static* fields.  However, when talking lightning 
or RF, an external magnetic field induces currents in the Faraday shield 
that (ideally) cancel all magnetic and electric fields inside.  As 
others have said, the cancellation depends on the conductivity of the 
shield (at RF, allowing for skin effect) and the maximum mesh opening, 
if any.  If you want > 100 dB isolation, you will have to work at it.  
Doors and ventilation (not to mention cabling and windows) are 
particularly difficult to manage.

Hopefully, we wouldn't want the cage to take the full force of a 
lightning strike, but current carrying capacity still might be a 
factor.  Aluminum foil is probably not the right material for the job.

73 Martin AA6E

-- 
Martin Ewing, AA6E
aa6e at ewing.homedns.org
+1-203-315-5160