Here are my observations on Beverages -
Short Beverages (300 to 400 ft) 'can' be useful.
I have a 250 ft Beverage due east which I use
primarily on 40M for Africa, BUT, at times it
surprises me how well it hears on 160.
(It used to be 500 ft until my neighbor to the
east cleared part of his woods for a pond :-)
IMHO, the best length for triband (160, 80, 40) use
is 500 to 600 ft. I gave up trying to maintain terminating
resistors in the woods and since my friendly neighbor
to the west sold off some of his property, I can no longer
run wires to the West so I just listen off the back of the
unterminated wires. W8JI is absolutely correct that
an unterminated Beverage is not truly bi-directional.
My unterminated 800 ft East Beverage just doesn't
hear stations from the Pacific as well as I would like
on 160M.
I have developed a bi-directional design which will be
published soon (I hope). I find they hear as well as
my end fed Beverages in the favored direction, and
seem to be about 3 to 6 dB stronger off the 'back'
of the unterminated Beverages.
I realize that unterminated and / or Bidirectional
receiving antennas are not quite as good as a properly
terminated and properly fed Beverage. That said,
my unterminated and bi-directional wires DO hear
better than my transmitting antennas most of the
time and have been 'good enough' for me to work
322 countries on 80M with single verticals and dipoles.
For 160M, I found a 1000 ft Beverage sometimes
provided as much improvement over my 500 footer
as the 500 footer provided over my vertical. On
80M, the 1000 footer seemed 'dead' in the early
evening but 'came to life' several hours later. My
guess is that waveangles at / after sunset are
higher and the long Beverage was not hearing
those higher angles.
>From the eastern USA, three Bi-Directional wires
at 30 / 210 (or 45 / 225) , 90 / 270, and 150 / 330
degrees give nearly complete coverage of the world.
A North / South antenna from East Central USA
is not needed. Stations from over the pole usually
seem to arrive at skewed angles either side of the
pole or along the terminators to the south. From
here, the only areas due south are Central America
and CE0 which I hear just fine on the SSE and SSW
antennas.
Tom N4KG
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