"art" wrote in message
oups.com...
Tom, this is well written and devoid of any antagonism towards anyone.
If anybody wants to dispute any point then all relavent data is in
place in your posting and thus
forces all who disagree to stay on subject without the need for
extraneous data when debating their differences. There will ofcourse,
be some that will be more interested in a fight or profanity in the
absence of comunicable knoweledge , but you are well positioned to just
stand by your posting without retaliating in kind.
Well done
Art




Here is the exchange on the subject from TopBand reflector:
K3BU (...)
and W8JI responses:

Tom is confusing Faraday shield with Electrostatic shield
and whole reasoning that the grounded shield of small loop
antenna is THE antenna is all wrong. Wire loops inside the
electrostatic shield are perfectly OK to receive the RF
and ARE the antenna.

It's a very well known property that nothing passes through
the walls of a shield more than several skin depths thick.
This is because skin effect keeps the current in the outside
layers and the core of the shield wall is dead. This is the
very thing that allows our coaxial lines to behave like
three conductors, a center conductor, a inner wall, and an
outer conductor. The physical behavior of a shield does not
change with application.


Electrostatic shield in small loop antennas reduces the
interference, electrical noise locally generated (prevalent
electrical fields).

Not so Yuri.

First an electrostatic field by definition is a non-changing
field. Static is stationary or unchanging, and things that
aren't changing can't make RF noise.

(Here he is confused about electrostatic shield, "electrostatic field" and
electrical field and just like with loading coils case, confusing the issue
with behavior of ALL shields, Faraday, Electrostatic, coax, etc. applied to
a wrong case. - Yuri)

The field from an accidental transmitter (noise source) is
just like the field from any intentional signal source like
a transmitter. There is absolutely nothing that says the
field has a high field impedance (electric field dominant).
Even if it was a high impedance at the source, just 1/10th
wave or so from the source the field would change to a low
impedance.

We can't filter noise by virtue of field impedance or a
shield. Even if we could, the noise source in the nearfield
would randomly field dominant depending on distance and
source charateristics.

The only thing the shield can do at radio frequencies is
change the system balance.

73 Tom