--------- Begin forwarded message ----------
From: martin38945
To: congress@magpage.com, ed.welch@cheaha.com
Subject: Re: Radials...directivity, gain?
Date: Mon, 17 Feb 1997 09:18:03 PST
Message-ID: <19970217.091613.7199.1.martin38945@juno.com>
References: <199702171226.HAA20218@alaska.magpage.com>
Dear Jim, Ed, and friends,
When I was a youngster, just coming up in Ham Radio, there was an old
timer in my hometown in WV who often bragged about his one element beam
on 40m. I knew he wasn't joking because he could reduce his signal to me
(abt 3 miles east) substantially. Yet we all knew he was doing something
real because people west of him would see a big increase when I saw the
reduction. But he would never let any of us know what he was doing. He
was a big contester at that time (primarily Sweepstakes) and he took
particular pleasure in keeping his "secret weapon" a secret.
We would actually go spying around his QTH to find the one element
beam... whatever it was... (we had no idea what we hoped to find). All
we ever saw was this bent up old Gotham vertical. He had it mounted with
the feed point up about 20 feet. He had a wooden ladder to it's feed
point. We presumed that the ladder was to get at the base loading coil.
He had five elevated radials: one pointed at Europe, one at JA, one at
Africa, one at South America, and one at VK. The elevated radials sloped
down to about 15 feet. But it was years before anyone ever figured out
that the ladder was there to manually switch to the single radial he
wanted. We all thought it was there to change taps on the coil.
Years later (he is a SK now), he admitted to the whole scheme and freely
told people what he had done. And you know what? More often than not...
he was disbelieved and the majority of the old timers thought he took the
mystery of the one element beam to his grave. But I believed him and
tried it. Take my word for it... it works.
I have never attempted it with ground level radials. If I can't elevate
the radials... I don't use a vertical. I have no interest in proving
that 90 radials is almost as good as 120 radials. I would rather use the
time to operate. It is my firm belief that a good set of elevated
radials... no more than eight... produces a superior signal to anything I
would ever take the time to ground mount.
One thing I have learned over the years... relay switching of the radials
is very tricky. That is why the OTer I mentioned always climbed the
ladder. He realized that coupling across the relay contacts effectively
kept all the radials in the circuit... at least to some degree. Any
switching arrangement with five radials will be a compromise because all
the radials will effect the field even when only one is switched in.
However, in most of my installations the interaction has been acceptable
to me. Even with relay switching, I see about two S units favoring the
desired direction most of the time. Notice I say "Most" of the time.
There are many, many factors involved.
Sometimes it helps to move the radials slightly off the correct heading
to compensate for the interaction and skew of the pattern.
An ideal installation, I believe, would be one with a single radial that
could be tied to five or more tie points and manually 'walked around' to
the desired location. My own experience has shown this to be the sure
way of getting good directivity without skewing. However, I don't fancy
walking around my lot in sub zero temperatures so... I have usually gone
back to a switching arrangement.
That is the story of the one element beam as I know it. Hope you got a
kick out of it.
Very 73,
Martin W9XN QRP-L #998
--------- End forwarded message ----------
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