The title of this thread threw me at first. But now I see it for
what it is, and that is using multiple dipoles with one
feedline. I've never had any luck with putting them in parallel,
but if I would run them with the wires say, running N-S, E-W,
then that works fine and is easy to get a good match on both
bands. Our local radio club had one for 3 bands, 40/80/160 that
was getting pretty ragged, so I built one like that before the
2003 Field Day. Same theory applies, although of course you
can't separate them as well. We separated the legs as best we
could, and were able to get a good match on all 3 bands.I've
seen the parallel setup in antenna handbooks, but I've never
been able to get them to work. The low frequency dipole was
always the dominant one, and had a good swr. A friend bought one
of those 40/80 parallel kits at Dayton a few years ago and never
could get the 40 swr down. I suggested that he try spreading the
legs apart, and that solved the problem.
Mike - K9MI
----- Original Message -----
From: "n4lq" <n4lq@iglou.com>
To: <tentec@contesting.com>
Sent: Monday, August 23, 2004 11:37 AM
Subject: Re: [TenTec] grounding dipoles
> You can have a lot of interaction between parallel dipoles.
Some antenna
> current will flow the unused antennas no matter how you try to
avoid it.
> Depending on which bands you try to parallel, the results will
be mixed.
> Often, high swr and narrow bandwidth is the result. I have had
good
> results with 80,40,20 paralleled as an inverted vee and
drooping down
> around the pole like a maypole. I tried putting them all in
the same
> plane and ended up with horrible swr problems. 40m and 30m can
really get
> crazy. 80m and 160m will work but yields very narrow 2:1
bandwidth on
> both bands. People have been doing this since antennas were
invented.
> Read any book about antennas and you'll find this covered.
> Think about this: What if we cut a dipole for every frequency
between 1.8
> and 30 mhz and hooked them in parallel? We would end up with
two big
> sheets of metal about 250 ft. long and a mile high! What would
the swr be?
>
> Steve n4lq
> -----Original Message-----
> From: Able2fly@aol.com
> To: tentec@contesting.com
> Date: Mon, 23 Aug 2004 07:06:00 EDT
> Subject: Re: [TenTec] grounding dipoles
>
> >
> > In a message dated 8/23/2004 6:44:19 AM Eastern Daylight
Time,
> > jsb@digistar.com writes:
> >
> > I experimented with this once (once is the operative word,
about 15
> > years ago) ) but didn't have the best success with it
because the SWR
> > was high. Weather was bad and I was pressed for time so I
didn't
> > pursue
> > further. Does this require a tuner or should the SWR be
low? I would
> > very much like to eliminate the extra runs of coax, etc.
> >
> >
> >
> > ====================================
> > For minimum SWR, the dipoles of course need to be cut to the
proper
> > length
> > for resonance at your operating frequency. Formulas will
only get you
> > close,
> > then its "cut and try" time... Tuners generally aren't
needed for
> > resonant
> > coax fed dipoles, parallel connected or not...
> >
> > Bill
> > _______________________________________________
> > TenTec mailing list
> > TenTec@contesting.com
> > http://lists.contesting.com/mailman/listinfo/tentec
> >
>
> _______________________________________________
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