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YO Design Parameters

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Subject: YO Design Parameters
From: (Chuck Dietz)
Date: Sat, 28 Dec 1996 11:17:37 -0800 wrote:
> 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.

Chuck. KE5FI

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