Re: [TCML] Faraday Cage Safety

[Jim Lux <jimlux@xxxxxxxxxxxxx>]

On Aug 4, 2013, at 22:17, ACM de Queiroz <acmdequeiroz@xxxxxxxxx> wrote:

> Em 04/08/2013, às 17:53, Jim Lux <jimlux@xxxxxxxxxxxxx> escreveu:
> 
>> The hole guideline is for rf propagation via e field, not generally what you would be doing. 
>> the h-field (magnetic) isn't stopped by a mesh
>> 
>> The cage around a coil is more about stopping sparks.
> 
> The cage attenuates time varying magnetic fields too, because they induce currents on it that generate opposite magnetic fields.
But not field components that are perpendicular to the cage wall, since the cant induce currents in the wires.   In the far field with a propagating plane wave, the screen is parallel to the H-field

But close to the coil, the field doesn't look like a far field plane wave.   Try a simulation using NEC or similar with a loop for the primary, and the cage, an the current in the cage wires is tiny


> Care must be taken on wires entering the cage. They shall pass through filters, otherwise they works as antennas, and the cage then really serves just to stop sparks. It is actually very difficult to make an effective Faraday cage for this application. It would be simpler, and probably equally effective, to just use something to impede people from getting too close.
> 
> Antonio Carlos M. de Queiroz
> 
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