Windom Antenna Write Up

[kd-5-bgt]

I was looking around at various sites and ran across this write up on the windom antenna ...or off center fed dipole...

I found this to be very interesting and the theroies are sound from what I can tell.

I am also looking at buying one of these antennas for my HF station

Windom Antenna Home Pages

Good reading here

 

[W5LZ]

They are not bad antennas, I agree. There are one or two things in Mr. Roger's article that I don't agree with, but I figure that's about normal. The one thing to keep in mind is that a 'Windom' antenna is resonant only on it's 'design' frequency, the one it's length is cut for. It's use on any other (higher) frequency/band is harmonic related, and carries the same pros/cons as any other harmonically related antenna use.
Because it is sort of 'lop-sided', it can certainly make finding a place to hang it much 'easier'. It's also as 'variable' in shape, just like any 1/2 wave dipole, bend it, wiggle it around things, about like a roll-a-coaster except no 'loops', up/down/around, sort of.
Then you get to the 'catches', and all antennas have them. When you speak abolut harmonically related freq/bands and antennas you usually have a 'choice' of the 'even' ones otr the 'odd' ones (and in one instance that I am aware of, both). 'Even' harmonics are those that the lowest usable frequency can be multiplied by 2/4/6/8 and so on to come up with a usable frequency. The 'odd' harmonics are about the same except use 3/5/7/9 for the multiplier. The 'bad' part of that is that no matter if it's even or odd, the efficiency is always reduced in relation to how much power is in the signal being radiated. If you get 100 watts (round number) out on the antennas primary frequency, then what you get out at any higher frequency is going to always be less than that 100 watts. Can't get around that, that's the way it is. The -other- side of that harmonically related length antenna is that depending on which harmonic, the thing get's sort of directional, has 'lobes' and 'dips' that develop. If one of those 'lobes' happens to go in the direction you are interested in, hey, that's great! If one of those 'dips' or 'nulls' go in the direction you are intrested in, that's not so great. But then, it might 'cut-out' hearing something you don't wanna hear too, so it isn't always a 'bad' thing, maybe. Neat, huh? (And just exactly the same thing that happens with any 'harmonic' antenna!)
The use of baluns on a 'Windom' antenna, or any antenna, get's into some really weird pro/con type thingys. Meaning that there are some instances where the impedance transformation characteristic of a balun are never going to work out right no matter which 'size' balun you pick. The impedance of a harmonically related antenna never works out 'just right' so that one 'size' balun will work everywhere. There are practical limitations to that. Works out great in 'free space', almost never down here where everybody lives.
The other characteristic of a balun, converting from an unbalanced feed line to a balanced radiator. Since when is that 'Windom' a balanced radiator? The only characteristic of a balun that you'd be using is the impedance transformation one, right? So, if you used a feed line that doesn't much 'care' about balance in particular circumstances, and isn't going to be harmed by any impedance mismatch, then why not use it instead of coax which does care about those things? See where that's going?? Of course, doing that typically means having to have one other piece of equipment, a tuner. It also means that the feed line may 'radiate'. But then, except for one or two characteristics about that part of it, who cares if the @#$ feed line radiates? That can be as much a benefit as a fault you know.
Gobs of things to think about with this stuff! As far as I'm concerned, that's what makes it interesting.
- 'Doc

 

[kd-5-bgt]

Good points to ponder Doc !! Thanks

 

[dudmuck]

This GE Buck Rogers article might have a few issues.

First is the statements about ladder-line/twin lead is a bit misleading. This type of line will not radiate if its balanced, and will handle a wider range of impedances with less loss compared to coax.

Second is ignoring the improvements of angle of radiation with the carolina windom. The carolina windom adds a 10 foot section hanging from the feedpoint. This vertical section actually radiates, which improves/lowers the radiation angle. This section is choked off at the 10 foot point.

Another example of a great but simple antenna is a 135 foot doublet feed with 450/300ohm ladder line, with a 4:1 current balun connecting to coax to the tuner in the shack. Coax is lossy at the crazy impedances, but is such a short run that its of no concern. Ladder line needs to be kept away from anything metal or conductive, which often makes it difficult to run all the way to the tuner.

 

[Dealer]

Regarding said antenna, I use this antenna exclusive and have had the very best of luck with it.

Some things just work and this one works great and it is used by me this way.

I use it on the Even Harmonics Bands, 80 actually 75 meters after triming it some, and
40,20,10 meters...

I use a TS530s and No Tuner at all and output Is the same on 75 meters as well as 10 meters..

With a TS 50 and a AT 50 auto tuner, I work all even @ odd bands with no problem at all
and have full power out from both rigs.

From experience I will tell you some things that are a must do... Keep it in the Clear and that means at least 6ft. from tree limbs and do not run it over
Any buildings least of all any metal ones..

Follow directions to the tee and if you are going to run power then Up Grade the Balun..

There is a hot side or plus side if you will !! thats the long side and if and when pruning antenna DO NOT take off a even amont on both legs,
but instead take for Example 12 inches off long side then Only take 4 inches off short side.. or 1/3 of whatever..

I found the crimps will need to be replaced and not reused after triming as they just will not hold the wire afterwards.

Use coax seal on all exposed wire and on antenna feed at the balun.

If I were to do it again I would furnish my own coax and if, you are not going to use a center support then RG8x is the one to use as 213 will be to heavy.

I run a hundered feet of RG8x and found that a additionl 9ft was needed for the match ? also mine is at 35 ft on the ends with a 2 ft sag in the middle with no center support.

Also I am using the standard 1kw pep balun and not the high powered one, and if I was to buy today the high powered 2kw one is what I would get just for the Grins

If you talk to Buck and he gets testie with you Just Ask Him, what bit you in the Butt
and he will get right with you then !! sometimes Us old folks get up on wrong side of
the bed ! Its what happens when you stop getting any hehe

Hope this is of some help and catch you on the bands..


Best Regards,
John- kd5wjy

 

[hookedon6]

...If you talk to Buck and he gets testie with you...

LOL been there......... done that

actually, he (sometimes) gets that way because he does care and wants you to be happy with your purchase

 

[kd-5-bgt]

Thanks for the info guys,the more information the better on stuff like this.

I am still looking hard at this antenna

From what I have managed to figure out about dipoles(or almost any antenna) ,they are a comprimise at one point or another...
if it works great on band A it wont be as good on band B...something has to give somewhere

You just have to figure out what you can settle with and make it work for you