I don't consider myself an expert, but in my considerable experience with
G5RVs and similar antennas, any G5RV can be improved by putting an antenna
tuner
between the coax and the balanced feedline. If that is done, the balanced
feeder can be virtually any length at any frequency above 3.5 MHz.
73 Ray W2RS
In a message dated 1/31/2009 8:47:18 P.M. GMT Standard Time,
mathenyr@marietta.edu writes:
The G5RV has been well reviewed by several experts. The best review I
know of is by VE2CV and VE3KLO, in the ARRL Antenna Compendium Vol. 4.
The long and the short of it is this: A G5RV is a 100 foot long piece of
wire. The best way to feed that on multiple amateur bands would be with a
multi-band matching network a selected point on the wire. Then the
feedline (whatever type) would be in a matched condition and losses would
be least. An automatic antenna tuner would be ideal for such purpose,
mounted at wherever the feedpoint is to be located. If you can't put the
tuner up there, well-made openwire line will come close in performance,
with a proper tuner in the shack. You may have to trim the open-wire
length to get an easy tune on all bands. But the antenna is a 100 foot
piece of wire--with all the traits of any 100 foot piece of wire!
Adding baluns, stubs, coax, etc. as is often shown will only add loss
to the system. That loss is what improves the match on some bands!
Pattern wise, that feedpoint mentioned above should be at the center if
you want best results at 20 meters and below. If the higher bands are
your favorite, then there may well be a better spot...perhaps at an end.
But that will create other problems, and probably losses.
The marvelious thing, however, is this: Despite all that one can
find wrong with this "100 feet of wire" there are a gizilion and a half
of
these things out there making QSO's at this very second. It doesn't take
a great antenna to make a lot of contacts.
Ralph Matheny
K8RYU
207 Gibbons Place
Marietta Ohio 45750
mathenyr@marietta.edu
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