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Old May 17th 06, 05:17 PM posted to rec.radio.amateur.antenna
Yuri Blanarovich
 
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Default FIGHT? Here is another W8JI myth bone!


"Richard Clark" wrote in message
...
On Wed, 17 May 2006 11:30:55 -0400, "Yuri Blanarovich"
wrote:

Electrostatic shields work on principle of capacitance plate, being
grounded
and side exposed to electrical/electrostatic fields


There's a very simple test of this "shield." It relates to experience
and doesn't need for you to go to the library.

1.) Tack a wire across the gap.

Q. Do you still have signal?

A. No!? None????

Agree!
That makes it Faraday shield, which stops any signal from entering inside of
the tubing.
I never asserted that Faraday shield or closed metallic enclosure passes any
signals or fields.
We are talking about electrostatic shield, which if removed, antenna works
without change, you put it back, it still works the same way plus it rejects
in its reactive near field region electrical field interference.
If it was to be antenna, then when removed, the rest should stop working as
an antenna, or what is the theory?

Extra Credit Question:
Did the wire make the "shield" better, or worse?

It turned it to Farady shield and prevented signals from exciting the
antenna inside.

Extra Credit Question for professor:
Q1: If electrostatic shield is added to small loop antenna and it attenuates
the interference or signals from its vicinity, does it perform the function
of a shield or antenna?
Q2: Can the piece of tubing that is grounded by its outside surface, acts as
a capacitor's plate and provide the path to ground for electric field in
vicinity?

73's
Richard Clark, KB7QHC

p.s.
from your experience, the answer to the initial question above may
vary. If in fact it does, it may bring new material for discussion.


I just wish that points of discrepancy were addressed, rather than parties
taking off on tangents fitting their convinctions and trying to weasel out
of the wrong statements.

73 Yuri, K3BU