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Re: [TowerTalk] Multi-band HF antenna replacement

To: "Rick Stealey" <>
Subject: Re: [TowerTalk] Multi-band HF antenna replacement
From: "Rick Karlquist" <>
Date: Wed, 3 Jun 2009 10:25:50 -0700 (PDT)
List-post: <">>
Rick Stealey wrote:
> For sake of argument let's say I had one of the underperforming antennas.
> IF (but hardly anyone ever does) I had a comparison dipole mounted nearby,
> with an antenna switch to allow me to instantaneously switch between the
> dipole and the beam, presumably I would see the effect the testers
> measured.  But, lacking that, IS IT POSSIBLE that I could go on for years
> working DX, and not know any better?

Yes, people can and do work DX for years not knowing how bad
their antenna is.  Can you say "Gotham"?
Maybe hardly anyone has a comparison dipole,
but I do.  I religiously A/B with it whenever trying any new
antenna.  I remember one night I got a new antenna on the air
and a station in Senegal was coming in like a local.  I thought,
wow this is working great.  Then I switched to the reference
dipole and the 6W came in even better.  Turns out (long story)
the new antenna had a problem, now fixed, but we happened to have a
pipeline to Africa that night.

  I could rotate the antenna and see
> the pattern changes.  I might get good F/B, I might THINK I had gain and a
> good performing antenna.  Would I really know if I was not getting, say,
> the 6 db gain that the antenna was supposed to deliver?

You raise some good questions.  I would mention that you will always
have good rejection off the ends of a dipole driven element (unless
your balun is faulty).  You can easily experimentally tune a beam
for good rejection directly off the back, and a peak of sorts in
the front, but have a lot of power wasting sidelobes.  I agree
1100 watts is not dissipated, but it could go to waste in sidelobes.
You could possibly have sidelobes at high angles that don't show
up in a pattern test, especially on higher bands where the "unused"
elements are long.

Rick N6RK


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