Ladies & Gents:
Tom's (N4KG) comments are 'right on', and their is one additional
point of consideration with regard to fading -- QSB -- of an incoming
signal. That is the polarization of the incoming signal.
Many years ago, and no doubt more recently too by others, the late K6CT
did much experimenting from the Los Angeles area on 10 meters with
horizontal, vertical, and cross-polarized yagi antennas. His
conclusions were published in an Amateur Radio article - CQ I think -
sometime during the 1960's.
The general conclusion was that polarization seems to continue to rotate
and the cross polarized (two driven elements fed simultaneously, and
positioned 90 degrees apart) antenna was far superior to either of the
other two during weak signal times. It is recognized that a 3 db loss
occurs when feeding two driven elements simultaneously.
I recall talking with OM K6CT in the late 1960's about this, and he
explained that using identical receivers, feedlines, etc, on two
separate antennas while listening to the same station, the cross-polarized
yagi was consistently better at band opening and closing times, and during
general weak signal times. When signals were very strong the difference
was not so noticeable.
VHF folks have drawn a similar conslusion, since they use that type of
yagi on their satellite operations.
So, it does seem that there is more to weak signal receiving of an rf
signal than just lots of horizontally polarized gain, one horizontally
polarized antenna at any one given height.
73
Dale Jones, K5MM
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On Fri, 19 Sep 1997 07:09:38 -0400 (EDT) K4OJ@aol.com writes:
I am sure the major consideration in the development of this antenna
system was not the resulting gain, but the resulting consistancy on
receive of incoming signals as prop changed.....fading should be way
way down....
there is "always" an antenna at the right height!
.......................................
I don't believe it works that way, at least not if they are all phased
in at once. With all 8 antennas fed in phase, you will get one big
lobe at a low angle, (and possibly some well suppressed minor lobes at
higher angles).
To see high angle signals, the bottom antenna would need to be switched
in by itself.
de Tom N4KG
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