Well, don't have access to that reference. I'm sure that it would clarify
some
questions. Access to the once great Collins technical library is gone
(sigh).

Built a couple models in MMANA. One for a shorted loop, and one for an
open loop. As expected, the shorted loop is vertically polarized, and the
pattern
is in-line with the loop. [a magnetic flux pickup antenna].

Upon opening the loop, it forms a small dipole, with the two ends near each
other.
It is horizontally polarized, and the directivity is perpendicular to the
shorted loop.
[an electric field pickup antenna].

Of course it's hard to tell exactly the voltages that would produced by
these two
different antennas, and how they would combine, magnitude wise. Rough order
of magnitude in MMANA is they are within a few dB for a diamond shape, 1m on
a side at 3.5 MHz. But this would depend on how well the magnetic coil
coupled
to the dipole, and that's hard to tell in MMANA.

It would seem from this that the electrostatic shield does not necessarily
help
things because it appears to degrade the directivity [assuming the
magnitudes of the
two components are roughly similar ]. It would be interesting to see in
real life if
the shield did degrade the nulls of the unshielded loop (accounting for the
polarization
change).

-- Tom





"Tom Donaly" wrote in message
m...

Don't believe everything you read here, either. For a good treatise on
how the shielded loop works, and what it's good for, read Glenn S. Smith's
(Georgia Institute of Technology) article "Shielded Loop
Antenna" in Richard C. Johnson's _Antenna Engineering Handbook_.
73,
Tom Donaly, KA6RUH