"greg z" wrote in message
...
I'm starting a project with some other guys on a 6M beacon
which will end up on a mountaintop at around 10K ft in New
Mexico. During winter, that means sub-zero temperatures,
high winds, and ICE build-up on everything exposed. We would
ideally like to put up an omnidirectional horizontally
polarized antenna like a loop. Anyone have experience with
building (or purchasing) such an antenna that would be
sufficiently bulletproof to stand up to a severe weather
environment? We could go vertical, of course, but since this
beacon will be operating in a CW weak-signal environment
under a wide variety of propagation modes (including ground
wave, troposcatter, etc., where polarization is more
important than it is with ionospheric propagation), we'd
like to stay with horizontal if it's physically realistic to
do that. What we don't want to have to do, however, is trek
up to the mountain top every weekend to put the antenna back
up. g

Bill / W5WVO
Albuquerque NM


Omni (quasi) loops for V/U are open at the far end
HF loops (typically 1 wavelength) that are closed loops) have a pattern
almost identical to a dipole- i.e. not even close to omni
Dale W4OP

On Sun, 08 Feb 2004 17:51:32 GMT, "Dale Parfitt"
wrote:


"greg z" wrote in message
...
I'm starting a project with some other guys on a 6M beacon
which will end up on a mountaintop at around 10K ft in New
Mexico. During winter, that means sub-zero temperatures,
high winds, and ICE build-up on everything exposed. We would
ideally like to put up an omnidirectional horizontally
polarized antenna like a loop. Anyone have experience with
building (or purchasing) such an antenna that would be
sufficiently bulletproof to stand up to a severe weather
environment? We could go vertical, of course, but since this
beacon will be operating in a CW weak-signal environment
under a wide variety of propagation modes (including ground
wave, troposcatter, etc., where polarization is more
important than it is with ionospheric propagation), we'd
like to stay with horizontal if it's physically realistic to
do that. What we don't want to have to do, however, is trek
up to the mountain top every weekend to put the antenna back
up. g

Bill / W5WVO
Albuquerque NM


Omni (quasi) loops for V/U are open at the far end
HF loops (typically 1 wavelength) that are closed loops) have a pattern
almost identical to a dipole- i.e. not even close to omni
Dale W4OP


Huh!? According to the article on L. B. Cebik's web page, a
one-wavelength horizontally oriented, horizontally polarized loop
antenna has a nearly circular pattern. As a large loop is driven by
increasing frequencies, the pattern becomes more like a starfish, but
it radiates relatively symmetrically in several directions, the number
of lobes increasing with frequency. A dipole has a broad
figure-of-eight pattern and a pair of strong lobes with minor
lide-lobes as it is driven by increasing frequencies. Try modelling a
dipole and a closed loop and see for yourself, don't believe me.

Russ

Russ wrote:

"Dale Parfitt" wrote:
HF loops (typically 1 wavelength) that are closed loops) have a pattern
almost identical to a dipole- i.e. not even close to omn

Huh!? According to the article on L. B. Cebik's web page, a
one-wavelength horizontally oriented, horizontally polarized loop
antenna has a nearly circular pattern.

Dale is obviously talking about a vertically oriented loop. And
a one wavelength horizontal loop is not a good omnidirectional antenna.
--
73, Cecil http://www.qsl.net/w5dxp



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