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Old April 3rd 09, 07:59 AM posted to rec.radio.amateur.antenna
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Default multiband resonant radials

On Fri, 03 Apr 2009 00:36:10 -0400, Tim wrote:

Ok, looking at fig. 6 of the pdf, 4 bands,2 wires. I assume that the
long top wire is somewhat resonate on 40 and 15, with the clipped wire
being for 20 and 10. That means one wire is both 1/4 and 1/2 wave.


Hi Tim,

I already offered my best guess on that. Conversion of feet and
inches to meters gives the story.

I should have looked better at that because I am picturing a 1/4 wave
vertical with a half wave radial...Or with rf, wouldn't that matter?


It is only half the story. What the vertical element offers is the
other half. The natural presumption is that it is a quarterwave in
its own right, but with HF Multibanders, that can be a presumption too
far. As they are generally loaded for the lowest band, tuning is
difficult, narrow, and performance seems to suffer there (from my own
experience with a GAP and other's reports of theirs).

So then on my triband vertical idea, I would be better off staggering
radials around in a fan shape, say one every hour of rotation, (3 bands,
4 radials) and have four resonant radials connected by some insulating
material for mechanical stability. Harder to make but easier to tune.
Going to look like a multi band vhf antenna on steroids, but as long as
it works......


It probably won't be as easy as that, but it won't be as hard as
anything any more cute. Even then, the shortcuts often work if you
observe all the "gotchas," which usually means lifting the contraption
into the air 10 feet or so.

73's
Richard Clark, KB7QHC
 
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