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Old August 31st 16, 09:34 PM posted to rec.radio.amateur.antenna
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Default U dipoles

Ralph Mowery wrote:
In article david_ryeburn-9073AE.11364031082016@88-209-239-
213.giganet.hu, says...



Here's a different suggestion. Put up as long a section (horizontal
except for the sag) as you can between the two trees. Say you can get
115 ft that way. Then extend each end 10 ft by adding a vertical wire
dropping down. Now the high current point on 80 m is way up in the air
where it will do the most good and the antenna won't be as much of a
cloud-warmer as your non-inverted V would have been.

Yet another suggestion: Just put what you can up there between the two
trees. So it's 20 ft or so short. Feed it with home-made open wire
(second choice: ladder-line). Use a good tuner. The main problem with
antennas slightly short of a half-wave long is that they have relatively
low resistance and appreciable capacitive reactance so feedline losses
go up. But if you use really low loss feedline they can still be pretty
good. For use on harmonics there is some advantage to avoiding an actual
half-wave on 80 m since that will have very high impedance on even
harmonics and with some feedline lengths can be very hard to match.

David VE7EZM and AF7BZ


Thanks for all the ideas. That is not the only antenna I have for the
low bands. I do have a 60 foot tower and triband on it. Also an off
center fed antenna in another directionthat is long enough to be almost
flat.

If one of the ropes had not grown into the tree, I might be tempted to
try loading it near the end, but I can not get that end down now.

Most of my work on 80 meters is just some friends in the state and not
not much DX so the cloud warmer is really to my advantage on 80.

I was just courious as to what patern it may be for that U or V shaped
antenna as I don't recall seeing a computer plot of one. Just the flat
top and inverted V antennas.



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In free space, and inverted V and an inverted inverted V have the same
characteristics. The issue here is that the center is close to ground
which will have a big effect on the pattern.

--
Jim Pennino
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