[Elecraft] Very short 80m antenna
Vic Rosenthal 4X6GP
k2vco.vic at gmail.com
Sun Jan 22 07:34:54 EST 2017
Today I am limited to the bands from 7 MHz and up and I want to get on
80m. My space is very limited, and in particular (due to the need to
rotate my existing dipole), there is no way to put up a vertical more
than about 3m high, and no room for radials longer than a few meters.
But the location is 35m above the ground and it is possible to add
another rotatable horizontal dipole to my mast.
So I am thinking about a 6m long dipole made of aluminum tubing. I have
some that is about 20mm in diameter. I will make capacity hats for each
side to add some end loading.
Yes, I know the bandwidth would be very narrow. But I could live with a
3:1 SWR bandwidth of 30 kHz.
I'm thinking about two possible configurations for loading coils: one
coil in the middle, or two coils, each about halfway down each side of
the dipole.
I know that two coils would produce a more efficient antenna. But the
one coil in the middle has two big advantages: it would allow me to feed
the antenna via an isolated link, which would solve the common-mode
problem without requiring a balun, and it would allow for easy tuning
and matching.
So what do you antenna experts think? One or two coils? Or is it just
crazy to expect anything from such a short antenna?
--
73,
Vic, 4X6GP
Rehovot, Israel
Formerly K2VCO
http://www.qsl.net/k2vco/
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