Rcv'd some excellent encouragement from W4RNL and
N4KG, re the double, 4-wire V beam idea. LB, W4RNL
ran a model through EZNEC-4 (W7EL's version of NEC-4).
His data is very nice, but, as did N4KG, he found
they would perform best if fed separtely as real
V-beams. He found no interaction with the unused
wires, and up to 9.5 dBi with 17 degree launch
angle on 40 meters. The patterns are "very wide,
shaped like a spreading tulip in both lobes". The
rear lobe will be down about 2.5 dB from the lobe
out the mouth of any one of the V's. The mouths
of these V's will be about 2 miles from the Pacific,
at a height of about 500 feet above the water
surface; and over the ravine (small valley) on
unused plantation land behind my QTH. Center of the
wires will be over 100 feet above the valley
floor, the ends about 40 feet above the ravine
rims, terminating in insulators from rope up in the
trees on the mouth end, and from my antenna "tower"
here.
Also some interesting results
wired up as I had suggested yesterday (and even
when feeding only wires 1 and 4, making a loooong
(1120 feet) wire, center fed, but bending at
the center at a 150 degree angle!) Conncting wire 2
to 1, and 3 to 4, as I had conjectured, resluts
in a diamond shaped pattern per EZNEC; rather like a
vertical, except there is a predicted 7 dBi gain
at the four diamond "points" with take off angles
of 19 degrees.
To do this, both of them suggested using
3, or even 4 DPDT relays set up in a remote box up
at the antenna feed point. LB's model showed probably
no need to home brew a 600 ohm ladder line, just use
the now available 450 ohm, supers flexible, #14
twin lead available from Radio Works or Cable X-perts.
But, need a source for DPDT relays that can handle some
higher VSWR that will probably show up from time to time
as I power these up to the output of the 87A on any of
the bands, 160 and up!(Excepting 30m, of course, hi).
So need some ideas for sources of relays suitable for
switching 450 ohm ladder line. Probably should be
double coil types, that is, when not switched
one way or the other, should rest in the center, with
the armature contacts open.
Thanks and 73, Jim, KH7M
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