Hi Mike,
I once built seven two wire Beverages at the Cuesta College Radio Club.
I used the method explained by Misek in his book Beverage Antenna
Handbook. I believe that several issues of the ARRL Antenna Book also
describe the two wire reversible Beverage. Mine did not use any
terminating resistors, at least not at the antenna ends.
In a two wire reversable Beverage there are two feed transformers at the
same end, most likely the end nearest the shack. One of these
transformers feeds the two wires in differential (push-pull) mode and
the other transformer feeds the wires in common mode.
At the far end one wire is grounded and the other is left open. There is
an alternate method which uses a transformer at the far end. I never
tried that method, I suspect it may be better in some ways.
The differential mode feed transformer uses the two parallel Beverage
wires as a transmission line to feed the antenna from the opposite end.
The grounded and open wires reflect the signal in opposite phase, which
feeds the two wires as a transmission line all the way back to the
differential mode transformer.
The common mode feed transformer operates the antenna pretty much the
same as with a single wire one direction terminated Beverage.
I used two separate feedlines for the two transformers. The unused feed
went to a terminating resistor in the switchbox in the shack. And of
course the one in use went to the receiver input. I was using surplus
Wang word processor system cable, which is sort of like zip cord made
with two 75 ohm coaxes. I recommend two feedlines rather than relays at
the feed transformer box, if you have the cable, for the sake of better
reliability. And instead of terminating one feed, you can have another
receiver hooked up to it for your second operator to listen on.
They worked great, and if I ever get the space I'll do it again.
Enjoy,
DE N6KB
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