Inverted L for 20:
Have your horizontal lamda/2 wire fed at the other end.
Make the vertical feeding wire (single) the same length.
Voltage feed it on 20 and 40 meters with tuned circuit.
Current feed on 80 meters against 20 meter radial.
Horizontal wire on 10 meters height is at least 6 dB better for 20m band
than any simple vertical. But this antenna has some vertical radiation,too.
For 40 the radiation pattern is suprising good for domestic QSO and low
enough for some DX, too.
For 80 this is but a shortened top-loaded vertical with poor number of
radials, but it works.
Benny
OH9NB
On Tue, 3 Aug 2004 21:47:01 -0400, Guy Olinger, K2AV
<[EMAIL PROTECTED]> wrote:
For a single band, there is an interesting old-time alternative called
a single wire Windom. It is a horizontal halfwave with a single wire
feedline connected to the horizontal wire off-center. For 20 the
"dipole" part is 34 feet. The single wire feed is soldered to the
horizontal at a point 12.5 feet from either end and drops to the
ground.
The wire is fed against ground. The single wire exhibits a 400-450 ohm
feed against ground, regardless of the height of the height of the
horizontal under 3/4 wavelength. The vertical part radiates very
little. A poor ground that would ruin a vertical's performance at
20-35 ohms feed Z will do OK at 400-450 feed Z. As in a single 17'
radial wire just laid on the ground.
You can feed it with a unun wound on a toroid with a 3:1 turns ratio.
SWR on the low Z side easily matches 50 ohms well enough for coax or
any antenna tuner, without having to endure the high voltages found on
an endfed halfwave.
It has the predictable performance of a good dipole, without the
center insulator, and without the weight of a coax feed. If you use
something like flex-weave for all the wires it can be wound up and
carried around.
73, Guy.
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