Re: Faraday Cage

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

Original poster: "Paul Nicholson by way of Terry Fritz <twftesla-at-qwest-dot-net>" <paul-at-abelian.demon.co.uk>

Harold Weiss wrote:

 > Grounding will be made by a 8' copper ground rod, ...

If the cage is effective, there should be little or no RF current
flowing on this ground wire.

 > I am thinking of adding a separate RF ground for the coils.  Is
 > this separate RF ground okay?

No, leading the secondary base current out of the cage like this
will break the integrity of the cage.   The inside surface of the
cage becomes the 'ground' as far as the coil is concerned, so
attach the secondary base to the cage.  Avoid anything which
conducts RF out beyond the cage.

Be prepared for the coil's resonant frequency to alter.  The
proximity of the cage will increase the self capacitance thus
lowering the resonance.  At the same time, the shorted loop formed
by the cage will reduce the self inductance, thus raising the
resonance.  Expect a reduction in Q due to eddy current losses in
the cage wire, but this may be offset somewhat by a reduction in
E-field losses and ground return path losses.

Will be interesting to see how it works out.

How will you know if the external field is suppressed sufficiently
to be sure of not upsetting the pacemaker?  If it's not good enough,
the Old Man might need a reboot.
--
Paul Nicholson
Manchester, UK.
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