Richard you are a smart guy with respect to radio matters so you must
be misinterpreting things that are being said on this thread
That commercial radio stations use tines is evidence to me that they
serve a purpose i.e. electrostatic shielding, not everything, just
electrostatic stuff
( ignoring harmonics e.t.c. )
As for low frequency use, that would include audio, not just 50/60
which you refer to 'power . Now you say look at Terman and I have, not
only the section on transformers but on coupling circuitry...way back
to the days of spark gaps and ticklers, each of which are treated
differently by not only Terman but also by others. You will also note
that audio cables have sheet like covering just like books do with
TOTAL shielding. Pretty much all books on fields and waves have a
section of total shielding of nearby circuits with special reference
to TOTAL enclosure and the effects on circuits or inductances that are
so enclosed.
With all that being said and getting back to the initial area of
discussion
where Richard alluded to the picket fence. Why do you think that the
broadcast industry hung on to the ungainingly picket fence after all
these years and why would it not descriminate with regard to other
influences ?

Best regards
Art

Richard Clark wrote in message . ..
On 22 Dec 2003 21:06:44 -0800, (Art Unwin KB9MZ)
wrote:

Richard
I think you are confusing low frequency aplications with
high frequency aplications. A flat sheet allows formation of
ground loops that then form their own emissions.
This is not desirable in high frequency aplications and
thus a common short circuit to ground for discharge is required.
Best regards
Art

Hi Art,

I am confusing nothing. A current cannot be induced without a path,
if you do not provide any more than one terminus, there is no path
EXCEPT TO GROUND and it is a common shared by both halves of the
magnetic linked circuits (read your Terman). This means the circuits
on both sides of the shield are electrically decoupled from each other
and are driving ground directly - capacitively (the electric field).
The sole purpose of the Power Transformer's Faraday Shield is EXACTLY
for snubbing VLF/MF/HF/VHF/UHF coupling (there's no purpose to killing
50/60 Hz fields with a Faraday Shield, that just doesn't make sense in
the first place).

The guff you are repeating is the ill-understood concepts of UHF/SHF
circulating currents that could only be developed if the wavelength
scale can support it. Are you talking about 900 MHz applications with
3 inch Faraday screens? I think not.

There's no mystery about this, dimension and frequency drive all such
issues.

73's
Richard Clark, KB7QHC