> Chuck: You raise some valuable design tradeoff questions. In VHF/UHF
> contesting circles, a narrow beamwidth, max. gain antenna with forward
and rear sidelobs
> I would think these same design tradeoffs should be applied for the high HF
> bands, particularily 10M.
> On 10M when pointed to Europe, I've got a noise source to the rear.
> Accordingly, my 10M designs emphazize max. F/B ratios at the expense of
some forward gain.
I don't have any man made noise sources, however, on 10 meters I find a
lot of ionospheric ? geomagnetic? induced noise especially during high A
indices and in directions in which the band is closed. Many people think
this is line noise because it sounds very similar. Many times it will be
high toward South America in the evening if the band is closed in that
direction. If you are beaming for weak Asians, this noise off the back
of the beam might mask the desired signals.
If you have a 15 db gain antenna with a 10 db front to back you are
getting the gain of a good triband beam in the direction of the noise!
I prefer to make up for the high front to side and back in contests by
having multiple fixed beams which can all be fed at the same time or in
any desired combination. The most important is South America. I would
feel that any contest station should at least have a fixed South American
antenna. On 10 meters, the best height for me is 40 feet. It comes into
its own in the afternoons when the angle of arrival is high.
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