[TowerTalk] OCF Windom

[Jim Brown]

On Sun,8/28/2016 9:53 AM, Tom Osborne wrote:
> Some OT's will remember the single wire fed, Windom antenna that was
> popular back in the day.  There were a lot of these on the air.
>
> The Windom back then was a wire around 135 feet long, fed with a single
> wire, around 1/3 of the way from the end.
>
> What I am wondering is, is this actually a horizontal type antenna, fed
> with single wire, or it is more of a 'T' vertical, with the feed wire
> actually the radiator?

It is an off-center T. It's the current that does the radiating, and the 
current distribution will vary from one band to another.  If you look at 
the current distribution on 160 in an NEC model, most of the current is 
in the vertical portion, then it splits left and right where it hits the 
horizontal section. The currents in the top section are out of polarity 
with each other, so the radiation they produce is partially cancelled. 
In a Tee they are perfectly cancelled.  This an antenna that, like the 
various horizontal wires with parallel wire feed, is going to behave 
differently on every band. But those horizontal wires with parallel wire 
feed will have essentially the same VERTICAL pattern, while the vertical 
pattern of this single wire antenna will be different on every band. It 
will also be a better antenna on the lower bands than the higher ones.

> I think to actually be a vertical, it wound have to be fed against ground,

More correctly, against a radial system or counterpoise. Ground is as 
big resistor, so it's a terrible antenna element.

> but I have seen recommendations for using a G5RV type antenna by tying the
> center conductor and shield together and feeding it like a vertical.

Yes. I did that for 80 and 160 in Chicago with a real dipole that I fed 
with 75 ohm KW twinlead. My counterpoise was a big wrought iron fence 
that ran around the from of my lot. The dipole was at about 40 ft the 
shack was on the second floor, the feedline was somewhere between 
horizontal and vertical, and the wires running from the shack to that 
fence were part of the radiator. It worked OK but not great on 160, and 
was better on 80 than loading it as a dipole.

73, Jim K9YC