[AMRadio] Windom Antenna

[W7QHO at aol.com]

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 
> going
> to operate on, on the HIGHEST frequency the antenna will cover.
> 
> ie: 29MC /2 = 14.5, 7.25, 3.625, 18.125Mc.
> 
> 
Goeff,

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 
> then
> 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 
> to
> the
> open wire feed-line, the open wire line would have to go all the way to the 
> feed
> 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 
ground.

> 
> 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 
> some
> 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 
> 29Mc,
> but I simply fail to understand how one wire is going to feed an antenna 
> thas
> has two posts to connect to.
> 
See above.

> 
> Certainly has me thinking, though.  Now, if I could just come up with land 
> that
> had 300' (for guy supports on both sides)
> 
> I'll have to work CW on 3.6250, forget about 20m and enjoy a 
> multi-wavelength
> 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 
remember.

Dennis D. W7QHO
Glendale, CA