Rule of thumb, IMHO only, is that with an antenna below 1/4 wave you are
coupling a lot of your signal to ground losses, not sending it off to be
heard, and what you are sending out is at relatively high angles, not likely
to be compatible the best 'hops' to the DX.
But in some locations, that is all you can manage. Fifty feet is the
beginning of the 'happy zone' for a tri-bander, usually.
1/2 wave is where things start to work pretty well, and higher may be
better, but YMMV based on location. If you are on a hill with a nicely
sloping foreground, you can get too high.
The HFTA program from the ARRL Antenna Book will let you plot the local
topography of your QTH, and give you a statistical summary of the 'hops'
from your place to common DX locations, and let you pick antenna height(s)
that maximize your signals to those places. Even if you are on a flat
plateau, it helps to know the distances and most likely takeoff angles to
the desired stations Here in central Texas, for example, a low antenna at
30' or so will give you the better results into South America than a high
one, but for VU, the opposite is true.
Seldom, if ever, is one height best all around, and having low and high
antennas that you can switch is often very useful.
73 John N5CQ
-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of Jim
in Waco wb5oxq
Sent: Tuesday, July 30, 2013 9:46 PM
To: TowerTalk@contesting.com
Subject: [TowerTalk] How high is enough
When choosing a height for a beam is 1/4 wave above ground at the lowest
frequency enough? 1/2 wave? I see Force 12 rating the gain on their beams
at 74'1".
Why that height? At 20 meters is 100' a lot better than say 60'? I am
talking about relatively flat terrain. I see Stepp-ir makes a beam that
even has a 80 meter dipole in it. Would that workmuch better on 80 than a
wire dipole at an equal height? I have never had enough land to put upmore
than 50' bit nest year I might have over an acre and be able to go much
higher. I just wonder how high when you spend more to go higher than it is
worth? If I had the room for a wire dipole to run any direction, what would
be the best choice from central Texas considering being in the center of the
country east/west wise? I want to get the best bang for my buck! wb5oxq
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