Here's how it works:
1.) If multiple antennas with response in different
directions are directly mixed (at audio or at radio
frequencies) S/N ratio is always lost and some directions
will have phase nulling. It is always better to use ONE
antenna with a broader pattern if you don't every want to
miss someone from a null or lose contacts from signals
falling into the noise.
2.) If two antennas are put into both ears in stereo, it
still deteriorates S/N ratio. There isn't any destructive
phasing, just a S/N decrease. If the operator has the
training or ability to focus his hearing only on one ear
(one antenna) the S/N decrease will be less. If the operator
can't focus well on each ear independently, it will be more
weak signals lost. The amount is full of variables but there
will always be some stations missed. It will always be fewer
than if the two antennas are simply combined either at audio
(into mono) or at the receiver input.
3.) If you listen in one direction with good antennas, you
will always miss quite a few callers from other directions
in a contest. This is always true. Whether the number you
pick up in the favored direction offsets the number missed
just depends on the rates in the different directions and if
the stations you miss keep trying at other times.
The difference on many of my antennas between listening in a
favored direction vs. hearing something somewhere else is
huge, sometimes 40dB. That means an S9 plus signal can get
missed if the operator depends on hearing something "leak
through".
I think the best combination would be a low directivity
antenna in one ear and a directional antenna pointed in the
primary direction of activity in another ear.
73, Tom
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