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MF
Testing two antennas in diversity on signals around
EU seem to give the same results. Both antennas producing virtually the same
results, no one any better than the other, this is probably because with these
antennas the signals are strong and fade barely noticeable.
This is just a comparison test and not scientific,
therefore no measurements have been made. The object of the exercise is
to maximise the signal presentation on received signals for QSO purposes.
There is some fade noticeable at times but only minimal and signals are
perfectly readable both visual and audible all the time.
I have to check the system on long haul where fade
is noticeable especially the USA stns. One other point is antenna separation, my
antennas are not far enough apart, although they are clear from one
another.
Maybe two small dissimilar antennas, spaced
well apart would give discernable differences in diversity reception, a small
loop orientated towards the targetg signal and a small vertical or probe
type.
I have been watching SK6RUD and DI2AM most of today
and each has been strong throughout the day with virtually no noticeable fade
observed on either antenna.
Antennas tested are :-
190 metre loop, 40 metre loop and a 1/4 wave inv L
full size on 500 khz. The 1/4 wave is more lively than the loops, noise
increases but so does the signal, so its all relative. General noise level at
this qth is low, mostly atmospheric noise.
As described before I am using two RX's and both
audio ouputs displayed separately to compare signal intensity. I briefly tried
one RX and two antennas but that did not look as good and was difficult to
balance each antenna, bearing in mind that cancellation could be a problem if
not engineered properly.
I have seen this method used in the past with a
properly designed front end mixer pre RX and each antenna's performance
visible on a meter.
This was on HF and was very impressive watching the
signal on one antenna peak while the other hardly produced any signal and
vice versa.
This was using two dissimilar hf antennas spaced
apart but only a 100 metres or so.
73 de mal/g3kev
73 de mal/g3kev
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