Doublet Length: More is better?
 

I'm putting up a centerfed doublet fed by ladderline and an antenna tuner in
the backyard and have two trees to support it which are about 112ft apart.

I could put up an 88 foot doublet between them easily. However would it be
better to put up a full 100 footer (allowing for endline support) since I
have to tune it anyway or is 88 foot a better choice?

It will be used for hambands as well as swl.

tnx
jtm

The G5RV sites mention that drooping the last 8 feet at either end
would have minimal negative impact on performance.

Would the same be true of a 80m dipole length of 133ft?

How much could be drooped?

tnx
jtm

wrote:

The G5RV sites mention that drooping the last 8 feet at either end
would have minimal negative impact on performance.

Would the same be true of a 80m dipole length of 133ft?

How much could be drooped?

Drooping has little effect on 80m but drooping 1/4WL on
each end can have major effects.
--
73, Cecil http://www.qsl.net/w5dxp


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More is not always better. As far as performance goes, some have suggested
that your antenna pattern can have more lobes (a bad thing) if you went with
the 100' of wire vs. the 88'. Having a very lobey pattern makes it hard to
determine where your signal is actually going, whereas having less lobes
usually means your signal will radiate at 90 degree angles to the doublet
antenna.

See an article describing this at:
http://www.cebik.com/aledz.html

In the article, the author thinks 44' is the optimal length for a 40-10M
antenna and 88' is the optimal length for an 80-20M antenna, assuming you
want to maintain an accurate radiation pattern.

73,
Dan

"Jim Miller" wrote in message
...
I'm putting up a centerfed doublet fed by ladderline and an antenna tuner
in
the backyard and have two trees to support it which are about 112ft apart.

I could put up an 88 foot doublet between them easily. However would it be
better to put up a full 100 footer (allowing for endline support) since I
have to tune it anyway or is 88 foot a better choice?

It will be used for hambands as well as swl.

tnx
jtm

Dan wrote:
More is not always better. As far as performance goes, some have suggested
that your antenna pattern can have more lobes (a bad thing) if you went with
the 100' of wire vs. the 88'. Having a very lobey pattern makes it hard to
determine where your signal is actually going, whereas having less lobes
usually means your signal will radiate at 90 degree angles to the doublet
antenna.

EZNEC predicts the pattern very well. And the reason Mr. Varney,
G5RV, chose 102 ft. for his 20m antenna was to take advantage
of the beautiful cloverleaf pattern that allows me to hit
Europe, Central/South America, New Zealand and the Far East
with 10 dBi lobes without rotating my antenna. Quite often,
my fixed G5RV beats my rotatable dipole.
--
73, Cecil http://www.qsl.net/w5dxp


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