I have a MonstIR at 106 feet and a 2 element SteppIR at 40 feet.
I have done many direct A/B tests, correcting for the difference
in gain between the antennas. It all depends on the time
of day, as books will tell you. Early or late in the day,
the higher antenna could often be 10 or 15 dB better. But
in the middle of the day, no difference is usually observed.
This is over flat (VERY flat) ground.
The higher antenna doesn't necessarily hear better than the lower
one, even when the signal strength is stronger. This is because
the noise level is greater on the higher antenna.
I never observed a case where the low antenna worked better than
the high one. (Not saying it can't happen).
I also anecdotally compared RBN results on 20 meters with
nearby stations using 2 level stacks where their top Yagi
was lower than my single Yagi, and I beat those stations
handily, to my surprise.
So my working conclusion on 20 meters is the higher the
better, at least up to 106 feet, during appropriate hours,
over flat ground. This certainly doesn't apply over more
interesting terrain.
YMMV :-)
73
Rick N6RK
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