[TowerTalk] Off Center Fed Antennas

[john at kk9a.com]

I wish Tom was still on towertalk. I doubt that W8JI  is using an off center 
fed antenna when there are much better options. He describes the Windom on 
his web site and states the following:

Loren G. Windom, ex- W8GZ, was instrumental in the development of the Windom 
antenna. Loren lived in Reynoldsburg, Ohio. Loren was originally 8ZO from 
Columbus, Ohio in 1922. His call is now reissued.

Windom's original idea was off-center feeding a horizontal antenna to 
present a feedpoint impedance of 600 ohms. This is close to the surge 
impedance of a single-wire feedline, allowing an inexpensive single 
conductor to be used as a feedline.
In theory, with suitable selection of the feedpoint tap point and antenna 
length, a reasonable match should occur on multiple harmonically related 
bands.

The Achilles heel of the original single wire Windom is the single-wire 
feeder. It has no "return conductor" or shield, so the single-wire feeder:
1) radiates and couples to everything around it. This causes TVI and RFI and 
couples local noise into the receiver

2) causes considerable common mode currents along the feedline and at the 
matching system. The common mode currents and strong electric field 
extending a considerable distance from the feed wire causes RF grounding 
problems and common mode currents in the Hamshack and on all the shack 
wiring and equipment.


From:"Jim W7RY" <w7ry at centurytel.net>
Reply-to:Jim W7RY <w7ry at centurytel.net>
Date:Fri, 7 Jun 2013 09:17:45 -0700
List-post:<towertalk at contesting.com">mailto:towertalk at contesting.com>



-----Original Message----- From: Jim Brown
Sent: Wednesday, June 05, 2013 11:49 AM
To: towertalk at contesting.com
Subject: Re: [TowerTalk] Off Center Fed Antennas

On 6/4/2013 2:28 PM, Larry Loen wrote:

As long as we're talking OCF antennas, I've always found this an
interesting source as far as explaining them:

http://www.w8ji.com/windom_off_center_fed.htm


Yes. It should be noted that W8JI lives in the middle of nowhere, miles from 
neighbors. I'm out in the country, but my nearest neighbors are about 500 ft 
away, and I hear their noise.

No! He has a neighbor about 200 feet away from him... And many more down the 
road. Please see a satellite view of his property.
73
Jim W7RY