[Antennas] Dipole Height

Thu Sep 17 14:28:08 EDT 2015

Is anyone so familiar with antenna modelling software or has a library in
which such an example is given that can tell us the effective gain for a
dipole at 90 feet elevation compared to one of only 7 feet elevation? I
would guess at the take off angles of 0 to 40 degrees or so.
I was surprised at what a difference it made, there was a minimum effective
radiation that is needed at very low angles which are needed for long path
W1 to JA or SE Asia for example that a dipole at 120 feet elevation can
achieve but which a dipole up 30 feet cannot.
One thing I noticed in using a dipole at 120 feet elevation above ground is
that the real DX at sunset and sunrise sounded like weak garden variety DX,
so that VK3MR arriving long path at dusk on 40m sounded like a OK station
running 10w into a 3 meter high dipole!
I copied SQ3MR as Snowy's call several times trying to make him Polish
before it finally dawned on me he was VK3 not SQ3.
He used to use trees to support two diamond shaped bidirectional rhombics
of 330 foot leg length one aimed towards Europe and the other way toward
the USA, the bidirectional aspect covered both long path and short path.
His card:
http://gopher.floodgap.com/gopher/gw?gopher://sdf.org:70/I/users/djringjr/vk3mr.jpg
or by gopher (with gopher client or old browser that supports gopher (or
Overbite extension for Firefox/Chrome
gopher://sdf.org:70/I/users/djringjr/vk3mr.jpg
Not everyday someone posts a gopher:// link. :-)
73
DR