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
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