I suspect that this is not so much a matter of where the main
radiation pattern is, as where the nulls are in respect to the
incoming angles.
Very high antennas have better gain at the lower angles in marginal
conditions, and those extra db's at the horizon are worth a lot. But
the high antennas have deep nulls at common arrival angles. It would
be easy and common to have the arrival angle on a minus 25 db null in
the high antenna's pattern.
This would be the exact phenomenon accounting for being "stomped" by a
tribander. A 25 db null advantage to the tribander would be really
hard to beat.
Aside from getting some gain at very low angles, that's the main
performing reason for stacks -- avoid pattern nulls on angle of
arrival.
73
----- Original Message -----
From: "David L. Thompson" <thompson@mindspring.com>
To: <towertalk@contesting.com>
Sent: Friday, February 01, 2002 5:21 PM
Subject: [TowerTalk] Super high antennas on 10 to 20
N4KG and W4ZV are right. The real high antennas can be at a
disadvantage
after the bands open. I had a 7 el 10 meter beam at 70 feet in 1970
for the
CQ WPX SSB and I had a great signal into Northern and Eastern Europe
and the
Far East but needed to lower the antenna
to 40 to 50 feet when I got stepped on by a local with a 3el
tri-bander at
50 feet in G or HP (then KZ5 Canal Zone).
N4RJ tried all sorts of combinations and his final 10 meter set up was
35/65/90 and about the same proportion on 15 and 20. The 35 foot
antenna
was often left on South America.
Spend time on the lower antennas and only add antennas at 180 to 200
feet
when its the last option.
73 Dave K4JRB
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