[TenTec] Thoughts about the "Windom" or OCF antenna

[D.Cy Gacuzana]

Hi All... interesting posts on this, what appears to be, somwhat controversial antenna, the Windom, or OCF dipole if not single wire feed.  I just happened to trip upon this what turned into a balun thread, immediately after I accidentally stumbled upon the DXE print ad,  while searching for W9INN's ads in a real, not virtual QST magazine.  That prompted me to go on-line to investigate DXE's "New!" baluns.  
 
Two years ago (and still today),  I was searching for an inexpensive, efficient, no radial solution for an antenna. When I first got my ticket again not long ago, I thought the Carolina Windom to be the perfect magical solution, given it's claims and reviews. I've come to now believe most of the raves were the result of awesome propagation associated with the edge of the solar peak of two years ago, or simply the windom was up a half wave or more, combined with the fact that two years ago one could truly work the world QRP with rain gutters, if not literally some wet noodles.
 
When I finally could accept this, my mind turned to the idea of a classic single wire Windom, however, Pegasus being my All Purpose rig of choice,RF in the shack is absolutely intolerable.  (I can't do 15m over 20 Watts on my roof vertical, the computer goes bug-nuts- probably correctable by a change in coax length, as the air wound choke to augment my home-brew bead "balun" RF choke is no longer an option, because  I wanted to keep the coax as short as possible, I have not enough slack to roll a choke. Indeed, I IS a Newbie!). 
I could add a jumper long enough to make a choke coil for that band, but lately what I NEED is an 80m antenna with wider bandwidth than my current roof vertical of the trapped genre sporting 2 radials. So, 
 
Next came the idea of a base fed T,  however, at this point, my thoughts were that now I was into the realms of  Verticals, with all their pros and cons.  
  
I rather avoid a wires on the ground if possible.  Next came the idea of Cebiks center fed T, fed with twin-lead, but I knew of no 1:1 curent baluns available designed for such a purpose.  As well,  most of my operating time appears to be rag chewing of the CW variety- DX is fun, but I enjoy chatting a bit, so if DX chatting a bit can be had, right-on.  This seems rare, perhaps there are language constraints. Most of my rag chews appear to be North American, sometimes across the pond. So according to Cebiks diagram, T= great DX+ center fed T= radials won't significantly increase performance, BUT, T= big top-side NULL (guess that makes it great for DX!). Close in newly made on air friends might hear me poorly.
 
So next I thought, unbalanced T, and wait a minute what is that really? Looks like a classic Windom to me, fed at a 45 degree angle up top at the now Off Center.  But, to crush that idea, there was talk of all this,  guess the experts call them "common mode" currents on my feedline. To boot,  I could not find any data on how such a thing might perform, but I'm thinking the pattern would be purposefully distorted so as to afford good regional coverage as well as better than low horizontal wire distance coverage. Such an antenna, with a properly designed current balun slightly above ground-level might still hold some experimental promise, perhaps utilizing 1/4 wave counterpoises for each band of interest (maybe 8 wires on the ground is tolerable). 
  
The idea of a balun or matching transformer of some kind, at an elevated feed point has never held appeal with me, because of the weight as has been mentioned, and also because of what I interpreted to be loss associated with mismatches that would occur at some frequencies.  I prefer the idea of having no balun weight up there,  running some sort of twinlead (thinking 300 ohm windowline), using that feed as an impedance transformer via judicial length selection,  and accepting hopefully undectable by ear, losses- at the tuner- comprised of components and a circuit design which is intended to minimize those losses.
 
I realize I'm sounding very simply minded, but after all, I is a newbie.
 
I have mostly only read Cebik and ARRL Antenna, and a lot of posts concering baluns and tuners, geez, some of the debates can sure get hot! Seen a few on the Top Band reflector when my Uncle was thoughtful enough to forward pertinent posts to me and I got curious so I went and read the thread.  
 
 But, before then, when I first heard of the Carolina Windom, wanted to make my own, less lossy windom, as I was under the probable misconception that there might be higher loss than need be in a coaxial vertical radiator, and that two wires in parallel would have less loss at high SWR while it was doing it's "radiating." hi hi.
 
 Since then, I've come to believe, that probably the main reason an OCF might hold value, aside from being convenient, is to avoid extreme impedances when operating at frequencies away from the fundamental design frequency, in an effort to minimize losses in places like baluns and tuners when using balanced feedline.
>From what I can gather, losses are readily available to be had, especially within tuners of the T circuit variety "includes built in 4:1 balun" (probably Voltage if an older/budget design)- as if to imply this is the end all be all you need to connect to your balanced line of a length chosen for the sake of physical convenience, completely forgeting the impedance transformation properties of feedlines in general.  Just hook it up to enough line to reach the apex of your all band inverted doublet Vee and you'll be set to go! That was my interpretation.  Plenty of us non engineer "technologist" type newbies out here that read an ad and see it that way. 
 
So now, I'm leaning toward balanced feeline radiation not contributing much toward the gain of a windom, (though am not entirely convinced at all, that vertical feedline radiation on a classic Windom contributes insignificant gain when the single-wire feed approaches a quarter-wavelength or a skosh longer),   and therefore, I am hoping to believe that it may not be significantly detrimental, in the same vein.
 
I do believe that for parallel line fed antennas, having no balun at the feedpoint regardless of how you feed it, in a multiband application, is probably the best choice.
 
In searching for an antenna that would offer the most high and low angle radiation, for an all purpose multiband application, I came upon Cebik's pages concerning the Center Fed Inverted L.  Also read his Antenna's From The Ground Up.  For me, the appeal of the 60-66' per leg inverted L seemed to fit well, with a good compromise between horizontal and vertical radiation.  
I have one tall pine tree, maybe 80' tall,  roughly 8' the other side of my fence.  I'm thinking it may serve, as this tree's lower branches have been supporting my improperly fed 40m OCF wire for 2 years with no complaint. It's not my tree, how I wish!  
 
But next, I realized, wait a minute, I want 40/30/20/17 and the rest higher would be nice, too, however that whacko pattern fell.  Anyway, a mulit-high band horizontal dipole would be doable later in the early summer, vertical GP even, heck, even bite the bullet and get a GAP Titan, it covers the high bands, but- the big wire antenna must do 17m on down, because with 4 kids who knows when I'll be able to justify even but 320 bux on a Titan?
 
 I am no mathmetician- and looking at a most basic graphic of current/voltage distribution, and also evidenced by the theoretical feedpoint figures Mr. Cebik included with his All Band Inverted L compendium- I'm back to square one: Feeling the need to avoid extreme impedances. Which of course on 40 and 20, the center fed 80m 1/2 wave dipole has plenty to offer.
 
At this point I came full circle, and, as I already cut my 160m G5RV to OCF 80m length and will soon hack the coax off, I came to the conclusion that perhaps, this might work better for me, with an appropriate feedline length.  The end of the horizontal leg may have to dangle 10 feet or so, and the "horizontal" leg also would have to be  slanted- apex around 70' (i hope!), the end of it at about 30'.  The vertical leg would simply dangle from 70' mostly vertically, depending on the wind.
 
Whether or not I'd end up using one of the, for me, overkill expensive but probably worth it DXE baluns, remains to be seen, as the tuner I plan to use already has a 1:1 currrent balun- the tuner I'm thinking about is an auto tuner Pi-L depending on reactance values.  I have no amp nor designs on obtaining one any time soon.  Mostly, I hear guys with amps calling CQ and often are unable to hear the people answering, and for the ones they do hear well enough to call back, 80W would have worked almost as well anyway.  Nothing against amps and their use, perhaps some day.
 
So there it is, the whacko and unconventional OCF inverted L.
 
Any thoughts, comments, jokes, hoo-hahs or poo-poos are appreciated.
 
Thanks in advance
73.
Darin, W3DCG, Newbie in Atlanta.  
 
 
 


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