You just described the antenna I take camping with me and my K2. I have
an ATU on the original top so it works nicely. The flex weave makes it
very nice for throwing up and taking down. I can tie knots in the wire
and they come out fine. I tie a sheet bend to some mason's line and take
a few 2 ounce sinkers to whip them up in the fir trees. Or if I feel
brave I swing the lead weight around my head and let fly. Normally I can
get it right where I want with that method. Occasionally I have to duck
rather abruptly. Your mileage may vary :) I designed the Windom to work
on 80 meters so it takes a bit of string and two trees a bit further apart
than your 20 meter version. But in Oregon we have plenty of trees
(outside of the clearcuts). {Earth first; we'll log the other planets
later :)
73,
Kevin. KD5ONS
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.
----- Original Message -----
From: "Ron D'Eau Claire" <[EMAIL PROTECTED]>
I think it must have been self defense by someone. Some time back I
gave up
using the term "dipole" because the current crop of Hams seems to
think that
means a center fed antenna of some arbitrary length, rather than an
antenna
that is exactly 1/2 wave long and which might be fed anywhere.
So I gave up and started saying that I had a half wave antenna fed at
the
center, or at the end or off-center, etc.
But, since I like others to understand what I'm saying, I avoid
acronyms.
I take it the coupler at:
http://www.qsl.net/aa5tb/coupler.html
Is for QRP only! At 50 watts or so, I used to get flash-over in a wide
spaced air variable in that circuit. I used a large "Air Dux" coil
with it.
The voltages present at the end of a dipole are huge at any
significant
power level. I can't imagine the wire insulation on a toroid or a poly
cap
withstanding more than a few watts of RF there.
Ron AC7AC
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