This antenna is often called a "Windom" antenna. However, that is not quite correct. The original Windom antenna was fed by a single wire rather than an open wire feed line or by coax feed line, both of which have two conductors.
The regular dipole, which most of us are familiar with, has two halves that are equal in length. They are both a quarter wave in length and total a half wave in overall length for the antenna. It is just two quarter wave lengths of wire or whatever kind of conductor you desire, and the feed line from your radio transmitter is connected to the center of the antenna with one conductor soldered to each half of the antenna.
With the off center fed dipole it is connected the same way as a conventional dipole except that the feed line connections are center. For an 80 meter antenna You should make one leg of the antenna 45 feet long and the other leg about 90 feet long for a total of 135 feet. This changes the impedance at the feed point from 72 ohms to about 200 ohms.
On my 80 meter OCFD I made a 4 to 1 balun and put it right at the feed point. Then connected my Coax to the balun and ran it into the radio shack. I thought I was done then but discovered that I had a lot of RF floating around in the shack. So I made a coax choke balun and installed it right outside the shack.
I made the choke balun by simply coiling about 20 feet of coax into a 12 inch coil. That removed virtually all the RF from inside the shack and did not change the tuning of the OCFD.
Now the big question. Why go through all that fuss when a simple regular dipole would work on 80 meters? It's because It also now works on 80, 40, 20 and 10 meters with a 2 to 1 or better SWR which the tuner in my rig can take care of. It doesn't cover ALL of 80 or 10 meters with that low SWR but it does cover a significant portion of both and on 40 and 20 meters it covers all of the band with 2.5 to 1 or less SWR. So far It has worked into several states including Hawaii and Alaska as well as about 30 foreign countries. For DX stations it works into South America and Europe the best but that's because those areas are broadside to the antenna.
Regards and 73 DE K7RMJ
