I used a Bobtail years ago, the conventional three element kind. It worked
OK on 75 meters, but almost never as well as two inverted V dipoles
with 40 feet apex that were phased.
Mine was out in the clear between two trees over very wet rich black sandy
loam soil. I'm sure the good conductivity helped. I'm not sure about 40
meters, but it was good on 80.
For a low height antenna, it worked pretty well.
Watch some handbook formulas, using the formulas lengths are a bit wrong
(short). A ground screen under each element end also helps a lot, because
the electric
fields cause loss in the earth below the antenna.
I also tried a Bruce array, it was a dummy load on any frequency but the
design frequency and a real b**** to cut to frequency for optimum
performance
73 Tom
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