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Old December 12th 05, 04:41 PM posted to rec.radio.shortwave
 
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Default To RHF, et al. Re Loops

The loops respond to the magnetic portion of the wave, while most noise
is electrical.

In most loop applications, they are much shorter than a wavelength. At
least for shortwave.


Dale Parfitt wrote:
"Robert11" wrote in message
...
Hello:

Lots of good info on loops from posts. Thanks all.

Just want to be sure re this:

When you talk about a Horiz Loop, you mean a true loop where the end is
connected back to the beginning.

Right ?

(not just a folded random length config with a free end)

Any possible advantages in not connecting it back ?
(Interested in broadband, omni coverage)

Thanks,
Bob
There are very few configurations in which a horizontal loop offers a
quasi omni pattern- the one exception I can think of is when the loop is in
the vicinity of a half wavelength and the far ends are close. but not
touching- even here the pattern is not omni but elliptical in azimuth.

A 1 wavelength loop has a pattern nearly identical to a half wave dipole-
i.e. figure 8, slightly less gain than the dipole, and narrower bandwidth.

At other lengths, the loop, like a center fed wire, will devleop multiple
nulls. Of course, like the dipole at low heights, the nulls tend to fill in.

IMHO, I fail to understand the fascination with the loop configuration. If
it is a "quieter" antenna than a dipole ( and I can see no reason for this
other than the idea that it is a DC short) then a dipole could be made
equally quiet by placing a suitable choke across the center insulator.

Take off angle is identical to a dipole at the same height.
Dale W4OP