|[AMRadio] Windom Antenna|
W7QHO at aol.com
W7QHO at aol.com
Mon Dec 27 15:24:34 EST 2004
In a message dated 12/27/04 9:31:09 AM, w5omr at w5omr.shacknet.nu writes:
> So, in order for this to work, you have to decide what frequency you're
> to operate on, on the HIGHEST frequency the antenna will cover.
> ie: 29MC /2 = 14.5, 7.25, 3.625, 18.125Mc.
Presume the last figure should have read "1.8125 Mc.
> that being the case, then
> L = 468/f(L)
> L = 468/18.125
> L = 258.20689655172413793103448275862
Practically, we would ronnd this off to 258' 3"
> Now, you said that the 'tap is always feet times 25 divided by 180'
> T = 258.207ft * 25 / 180
> T = 6455.17 / 180
> T = 35.862068965517241379310344827586
Again, 35' 10" -- This is the distance to the tap-off point measured FROM THE
CENTER OF THE ANTENNA.
> Single wire feeding it? Fed against Ground? Doesn't the single feed-line
> become part of the radiating antenna?
Yes, yes and again yes.
> Even if someone were to take, say the output of a link and feed it directly
> open wire feed-line, the open wire line would have to go all the way to the
> point of the antenna, wouldn't it?
The feedline here is a single wire running up to the tap point. The flat
top is NOT broken apart at the tap point, the single wire is merely attached
there. The other side of the link (if this is the feed method used) would go to
> I'm sorry if I'm seeming a little dense, but I can't get unwrapped from the
> 'single wire fed version' of this antenna.
> Open wire output from the link has *2* wires. I can see attaching them to
> open wire line, and feeding this Wyndom antenna at 1.8125, and having the
> antenna resonant on 3.6250, 7.250, 14.5 (oops - can't operate there) and
> but I simply fail to understand how one wire is going to feed an antenna
> has two posts to connect to.
> Certainly has me thinking, though. Now, if I could just come up with land
> had 300' (for guy supports on both sides)
> I'll have to work CW on 3.6250, forget about 20m and enjoy a
> antenna on 10m (when the band is open). Pardon the sarcasm ;-)
These things actually do work and write-ups can be found in handbooks from
the 30's up into the 50's and later. There was usually a caution to run the
feedline away from the antenna at a right angle for at least 1/3 wavelength.
Worked best over a well conducting ground and feedline length could be
critical. Practically, some kind of a wire tuner would probably be required
especially for multi-band use. A good ground wood be important too. I used one back
in the 50's fed off a 6L6 with a pi network tank circuit. Worked well as I
Dennis D. W7QHO
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