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Comparison of Carolina Windom and 186 Foot Ladder Line Antenna
Robert Chimel (WA3LWR)
on
August 4, 2009
View comments about this article!
Hi,
I have been a ham for over 35 years and loved playing with wire antennas. It is amazing how much gain one can accomplish with some lengths of copper and a tuner. One question has been a comparison of a Carolina Windom type antenna and a 186 foot, center feed, with ladder line, antenna. During the past few weeks I did a receive comparison of the two antennas and found some interesting results. While this is certainly not a definite answer to the question of gain for these two antennas, it may stimulate some additional discussions.
Both antennas were mounted on 20 foot pipes at either end of my two story house in NE PA. Both antennas were home made, except for the Beldon 9913 and ladder line. Both antennas had very similar layouts of their legs, which sloped down and forward to different degrees. The center fed dipole was made as a sloping, inverted V antenna favoring the NW, and the Carolina Windom was set as a dipole which was slightly (about 20 degrees) short of 180 degrees and also favored the NW. On the one end it did drop about 20 feet, and the other end was about 5 feet. Needless to say, these are realistic conditions that most of us encounter with our neighborhood lots.
Tests were conducted during the last week of June and first week of July with the Sun Spots at a rather low level.
Results:
On ten meters, when it was open to the States, the Carolina won by 1 to 3 S units on my Icom 745, but five of the twenty times, both had the same signal readings.
Fifteen was too poor to get any reliable results.
On Twenty meters, about 20% of the time, both antennas had the same reading. Otherwise the Carolina was 1 to 3 S units stronger.
On forty meters, a slightly higher noise level was found using the dipole, as well as 3 to 5 S unit stronger signals on it. The Carolina lost.
On eighty meters a similar story was found. Nose was 1 to 2 S units stronger, but signals were 3 to 4 S units stronger with only 15% of the signals registering the same report. There was also more flutter on the dipole.
The 160 band was only tried in the early evening and here the dipole won easily with signals 4 to 5 S units stronger, but an increase in the noise level by 2 S units.
Why the difference? I only know that the dipole was longer than the Carolina, 186 feet to 135 feet. So, it is time for more testing and perhaps those with bigger yards can try various wire antennas against the Carolina as well as the beloved G5RV.
I hope to do a lot more testing and compare signals received at the other end to see if there is also a difference on transmit. Hopefully others will do the same and see what they find.
Hope this inspires others to try and see the differences.
Bob WA3LWR
This article has expired. No more comments may be added.
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Comparison of Carolina Windom and 186 Foot Ladder Line Anten
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by NN4RH on August 4, 2009
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Was this a "real" Windom antenna or one of those coax-fed so-called "New Carolina Windoms" they're selling these days?
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RE: Comparison of Carolina Windom and 186 Foot Ladder Line A
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by WA3LWR on August 4, 2009
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It was a homemade Carolina Windom with a 22 foot, RG58 coax vertical section between a balum and isolator.
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RE: Comparison of Carolina Windom and 186 Foot Lad
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by K0BG on August 4, 2009
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Interesting comments and observations. It would also be interesting to know the dynamics of the S meter in your 745.
The noise references are also interesting, because an increase in noise can also mean the antenna has more gain at that particular frequency. Therefore, noise in itself, isn't a very good indicator of worse/better comparisons.
Of even more interest, is where the individual stations were located. As you so aptly alluded to, antennas installed within residential lots aren't always mounted optimally. This causes their patterns to be skewed. Thus comparisons should be based on long-term observations, including the locations of the other stations.
Alan, KØBG
www.k0bg.com
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RE: Comparison of Carolina Windom and 186 Foot Ladder Line A
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by N8NSN on August 4, 2009
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Nice observations Bob.
I have been tinkering around with the idea of trying an OCF antenna.
The lot is certainly large enough to the northwest and south east...
I haven't looked in to it beyond a hand full of comments that OCF antennas have some RFI issues. I suppose that is mostly rhetoric coming from operators who experienced failed installations at one point or another.
From what I understand; the OCF antenna, was originally fed with a single wire coming up from an L network to a wire between 130 and 260 feet long at a point of somewhere around 27 to 30 percent of it's overall length ??? I am not sure on that.
For the sake of education... Let's say you have 135 feet of lateral length to work with... What would be the advantage and/or disadvantages of feeding this length off center as opposed to center fed and parallel?
If someone has EZ NEC Pro... Modeling these two at a height of say, 40 feet; what are the advantages or disadvantages?
Second question; What is the best way to feed an OCF antenna? Will parallel feeders work on a unbalanced antenna? I would presume that the feeders would radiate. But, isn't that part of the system of an OCF, that the vertical feeder radiates signal in a proper set up?
Sigh...
If I understand what I have read the OCF consists of a given length of wire fed at it's optimum percentage of over all length point with a 4:1 Balun; a given length of 75 ohm coax cable drops from there to a 1:1 balun and from there a random length of 50 ohm cable goes to the shack. Is this correct?
Has anyone tried replacing the 75 ohm vertical component section of coax with 93 ohm coax? I found a roll of 93 ohm coax at an estate sale and it has been used here and there in impedance matching experiments at the shack...
I know, I have a LOT of questions ;-D
73 & 72,
N8NSN (jim)
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RE: Comparison of Carolina Windom and 186 Foot Lad
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by K0BG on August 4, 2009
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Jim brings out a few peeves of yours truly.
The name "Windom" brings both good and bad to mind. The man (Wisdom) was an interesting guy in many respects, and I actually talked to him on the air a few times. But his version of the Windom antenna has transgressed even his wildest dreams.
Nowadays, it is more of less used to describe all manner of dipoles which are not fed in the center, but rather off to one side. The usually feed line is coax or ladder line, in difference to the original "Windom" which was fed by a single wire.
Any antenna fed off center will have a varying amount of common mode current flowing on the fed line. The common method of quelling the CMC is to use a balun, and typically a 1:4 voltage balun. A balun design which easily saturates under the reactances present. Even when a 1:1 current balun is used, there is still a lot of CMC, which is worse on some frequencies than others; factors which vary with the individual installation. Thus, some folks swear by them, others swear at them.
There has even been on "tri-pole" design published in the popular press, with references to a "penta-pole" version. Will it never cease?
The real truth is, off center fed antennas aren't magical, and they don't really have anything to offer over a properly designed, center-fed dipole, "OCF mavins" comments to the contrary.
Alan, KØBG
www.k0bg.com
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RE: Comparison of Carolina Windom and 186 Foot Ladder Line A
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by WW5AA on August 4, 2009
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I'm with Cebik, W4RNL. An OCF wire has no gain over a properly mounted doublet. The only advantage is the mechanics of fitting in. The disadvantage is that in many cases hams struggle with the RF generated in the shack. In limited use, the real single wire fed Windom, which is really a vertical with a top-hat does have some advantages.
73 de Lindy
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RE: Comparison of Carolina Windom and 186 Foot Ladder Line A
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by WA7NCL on August 4, 2009
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The OCF is all about the balun and isolator. Except for the possible mechanical convenience of the feed point, I don't see the advantage to it over feeding a balanced antenna with window line. Mostly its about how well you designed your balun to cope with the wide range in frequencies and varying impedances. Since most hams are cut and try types, I don't see how you can ever know what you ended up with.
The other thing about the article is the use of the term favoring the NW etc. This implies the author really knows what his radiation pattern is. I assume he means the wire is broad side to that direction?
I think what this article proves is that if you errect two different antennas with little idea of their actual characteristics, they will likely work differently. You should then switch between them and use the one with the best signal. This is a useful thing if you are just going to cut and try, which for a hobby is OK. Just don't fool yourself into thinking you are doing a science experiment.
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RE: Comparison of Carolina Windom and 186 Foot Ladder Line A
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by WG8Z on August 4, 2009
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Nice post Robert.
Two antennas,real world conditions, similar orientation, real time comparisons...Your results, let everbody form their own
conclusions....
Much better than a lot of the "This is the Cat's arse if I can hear em I can work em" stuff.
73 de Greg/wg8z
272'doublet w/450^
135' doublet w/450^
The end result of similar testing,
what worked best still hangs.
Anybody want to buy some coax and baluns?
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RE: Comparison of Carolina Windom and 186 Foot Ladder Line A
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by N0YXB on August 4, 2009
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Thanks for the interesting article. I'm genuinely curious what Alan means by the S-meter dynamics comment, since relative measurements are being made via the same meter. Please elaborate.
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RE: Comparison of Carolina Windom and 186 Foot Ladder Line A
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by K5END on August 4, 2009
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quote, "don't fool yourself into thinking you are doing a science experiment."
I think he pretty much covered that point when he ran the disclaimer in the very first paragraph.
"...playing with wire antennas."
"... a comparison..."
"...this is certainly not a definite answer..."
Sir, he TOOK THE TIME to write up his observations for your consideration.
"...it may stimulate some additional discussions."
He neither hypothesized nor postulated.
A more polite, formal or even civilized human response to the author would be something like, "Thanks for taking the time to submit your observation and experience. Very interesting."
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RE: Comparison of Carolina Windom and 186 Foot Ladder Line A
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by K5END on August 4, 2009
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Robert,
Thanks for taking the time to submit your observation and experience. Very interesting.
Larry
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RE: Comparison of Carolina Windom and 186 Foot Lad
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by K5END on August 4, 2009
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quote, "mavins"
Alan, I didn't know you speak Yiddish.
Sehr gut.
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RE: Comparison of Carolina Windom and 186 Foot Lad
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by K3AN on August 4, 2009
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This is useful A vs B experimentation, and the author wrote down or otherwise recorded the results. Good job.
Below is a link to another A vs B test that I suppose is also useful in its own way. Caution: it's snarky!
http://www.youtube.com/watch?v=vmpisOn4FmE
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Comparison of Carolina Windom and 186 Foot Ladder Line Anten
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by KK5IB on August 4, 2009
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I have an OCF antenna, 70' long, fed at 21' from one end, 25' high in the air the feedpoint and 15' at ends, fed with 52 ohm coax with a 4:1 balun at the feedpoint and a choke for RF in the attic about 10' below the feedpoint. The antenna was designed using EZNEC to have a low radiation angle on 20 meters, which is 19 degrees, and it has an SWR of about 1:1.6. By comparison, a 20 meter vee at 25' in the center would have a radiation angle of about 43 degrees. The antenna is resonant on even harmonics, 40, 20 and 10 meters, unlike a center fed dipole, which is resonant on odd harmonics. The antenna has less than 6:1 SWR on 40 through 10 meters, easily matched by my builtin antenna tuner on my Yaesu FT-900CAT. The antenna is far better on 20 meters than my 136' center fed zepp inverted vee with center at 40' and ends at 15', and radiation angle on 80, 40, and 20 meters of 90 degrees, straight up. Also real world comparisons between antennas and EZNEC were very close and useful. What I have found out is that wire arranged differently performs differently, you cna't tell simply by looking and guessing . Hope this is of interest.
Darryl, KK5IB
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RE: Comparison of Carolina Windom and 186 Foot Ladder Line A
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by WB2WIK on August 4, 2009
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>RE: Comparison of Carolina Windom and 186 Foot Ladder Line A Reply
by WG8Z on August 4, 2009 Mail this to a friend!
Nice post Robert.<
::Wonder if you know how close your call is to the "real" Windom? "Windy" Windom (as he was known on the air, I've worked him also) was W8GZ.
Pretty close.
WB2WIK/6
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Homework is a good thing.
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by N8NSN on August 4, 2009
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Alan,
I thought I had it correct with the paragraph about a true Windom being a single wire feed antenna with the 'cap hat'...
With no intentions to pirate this article, Alan; I am wondering if you had a chance to look over the "Modified 135' Doublet" article posted last week?
I respect your savvy on antenna knowledge and was curious on knowing your thoughts, but have not seen a reply or any e-mail from you on the write...
I have since simplified the wiring for the 4PDT relay, which opened up for use a pole and two of the throw contacts; and come up with another idea for adding a remotely tunable L Network circuit to either side of the arrangement or even both sides (balanced or single feed...) I think a 12X12 Cantex box would be in order for this... or perhaps even larger to house a 35uh motorized Collins ribbon inductor and a 300pf or so 3KV variable capacitor and drive motor, along with the bal-un and relay already there. I know the Dentron Bal-un isn't the best choice, but it's what I had on hand and it seems to work without puking from any over-saturation problems. Gotta love the large closet full of RF goodies ;-)
I posted the secondary schematic on my QRZ page if you want to have a look there and share some thoughts on the dealibob.
By the way, I did some research on the 4PDT 7KV relay made by Leach Relay Co. (Leach Corp, California) Well, the vintage ones like this are no longer available (new)... The cost on the vintage ones is, in a word, ridiculous... I found a 2PDT relay identical to the 4P... (but half the options / same KV rating) for a CRAZY 600 dollar ticket on fleebay...Oh boy, I suppose the kid at Cincinnati hamfest didn't know what he had... I didn't know either but, for a dollar a piece, they sure looked hefty for some parallel line switching mechanisms. None the less, I am very happy to know I acquired some really high quality relays on the cheap.
ALWAYS tinkering to reinvent the wheel in a simpler (not necessarily cheaper) fashion,
Jim
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RE: Homework is a good thing.
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by WB2WIK on August 4, 2009
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Nice writeup, Bob.
Would have been interesting to see a photo of the two antennas and exactly how they were installed. 20' masts on opposite sides of the house makes me think they were both inverted vees? A 185' inverted vee at only 30-40' above ground (or whatever, I'm not clear on its actual height) must have its end points down pretty low-?
It would also be interesting to know, if the antennas are both still "up," what occurs over time and distance.
When I compare antennas here, the comparisons are all over the map if I do it over just a day or two...it can take weeks to get meaningful data, and operating at all different times of day as well as contacts with stations at all different distances.
My last "comparison" logged 1000 contacts made over 3 months with stations from 400 to 11,000 miles. The long term data can skew results a lot.
Interesting, nonetheless! And it definitely pays to have multiple antennas for common bands, no matter what your interests. Never know which one will actually work better over a given path: This can easily change with the time of day, over the same path!
73
Steve WB2WIK/6
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RE: Comparison of Carolina Windom and 186 Foot Ladder Line A
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by WG8Z on August 4, 2009
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>::Wonder if you know how close your call is to >the "real" Windom? "Windy" Windom (as he was known on >the air, I've worked him also) was W8GZ.
>Pretty close.
>WB2WIK/6
----------
Yep Steve, I'm aware.
I have several Ham buddys who knew him well and shared some of Loren "Windy's" stories.
My choice of WG8Z (vanity) was influenced by that fact.
That and GZ being my initial's.
I don't post all that much however you are the first to notice the similarity. Hope to work you sometime as
6 land is no problem for me on 40 or 75 when the band is co-operating..Stubbing my 272' to act as a reflector for my 135' gets me a little extra kick to the West.
73 de Greg/wg8z
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Comparison of Carolina Windom and 186 Foot Ladder Line Anten
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by AI2IA on August 4, 2009
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If you noodle benders want to do it, you can drag this thread on to infinity.
YOU ARE COMPARING APPLES TO ORANGES.
When all is said and done, what progress have you made here?
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Comparison of Carolina Windom and 186 Foot Ladder Line Anten
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by K9CTB on August 5, 2009
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Nice article, Robert. I really enjoy reading reports by folks who take the time to do "side-by-side" comparisons. Thanks!!!
-----------------------------------
and K5END said:
Sir, he TOOK THE TIME to write up his observations for your consideration.
"...it may stimulate some additional discussions."
He neither hypothesized nor postulated.
A more polite, formal or even civilized human response to the author would be something like, "Thanks for taking the time to submit your observation and experience. Very interesting."
------------------------------------
Mr. Kendall, we don't know each other ... but I like you!
73 de K9CTB
Neil
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Comparison of Carolina Windom and 186 Foot Ladder Line Anten
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by W3NRL on August 5, 2009
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Bob
Thank you for your time in this matter.
I did the same comparison and got the same results
i still use my Carolina Windom and have many nice signal reports 59+ from all over the world.
I did this comparison for my own satisfaction and no body else. And i had fun doing it, making my own antennas. SO don't worry about the rest of the amateur community and there smart comments.
Just as long as you had fun doing it.
Thanks for you report
73 de w3nrl
Have fun!!!!!!!!!!
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RE: Comparison of Carolina Windom and 186 Foot Ladder Line A
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by K5END on August 5, 2009
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>"we don't know each other ... but I like you! "
There's one.
Only about 6 billion more to go. hihi.
TNX.
LK
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RE: Comparison of Carolina Windom and 186 Foot Lad
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by K0BG on August 5, 2009
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Jim, if you did, I missed it. Sorry about that, chief.
I guess it is just me... I do understand about properly choking common mode currents off coax feeds, when it is necessary. After all, if the RF can get out, it can get in too, and common mode noise is almost a byword for most amateur installations if the real truth be known. However, when you "have to" install a choke, just to get the antenna to "work" like it should, then something is wrong with the design. A fact, incidentally, Cebik mentions several places in his text on OCF antennas.
Larry, I even know what mashugana means, and in some respects, that's how I view OCF antennas.
Alan, KØBG
www.k0bg.com
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RE: Comparison of Carolina Windom and 186 Foot Lad
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by AB7E on August 5, 2009
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K0BG: "However, when you "have to" install a choke, just to get the antenna to "work" like it should, then something is wrong with the design."
Really?? I find that to be a rather careless generalization. I can think of situations where a choke performs an important task on a well-designed antenna. Two come easily to mind:
a. A choke at the driven element of a yagi to preserve pattern.
b. A choke (or even chokes) on the feedline of a ground-mounted vertical to deal with shield-induced currents caused by close proximity to the radials (unless the shack is located underground directly below the antenna).
73,
Dave AB7E
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RE: Comparison of Carolina Windom and 186 Foot Lad
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by AJ4MJ on August 5, 2009
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"I'm with Cebik, W4RNL. An OCF wire has no gain over a properly mounted doublet. The only advantage is the mechanics of fitting in."
I'm going to disagree with this ... slightly. OCFs present a more consistent feedpoint impedance, especially when it comes to harmonic operation. A 135 foot center-fed doublet will present close to 72 ohms feedpoint impedance at 80M. At 40M, it will rise to several thousand ohms. Take the same 135 feet of wire and feed it at 1/3 offset and you will see around 300 ohms at 80M. At 40M, you will see something also in the hundreds of ohms range (sorry I'm at work and don't have EZNEC in front of me to come up with exact numbers).
This doesn't make the antenna "better", it just means that if you feed it through a 4:1 or 6:1 balun, that your tuner will be presented with less of a mismatch. If you are using a tuner with limited matching range (such as most autotuners built into rigs), this could make the difference between being able to use the antenna and not.
Also, if you wind up having to run part of your feedline as coax (between the tuner and balun), you will experience lower losses the closer it is to 50 ohms.
I built a 135 foot OCF antenna for a friend. We hung it at 45 feet and the feedpoint was 22 feet from one end. After feeding it through a 4:1 balun, SWRs for all amateur bands 80-6 were below 5:1 and in many cases were below 3:1. He was able to use his rig's autotuner, which was a lifesaver since he's blind.
A center fed doublet certainly will work. I built one of these, too. I used a manual tuner and it had sufficient matching range to handle the high impedances through a 4:1 balun. Nothing wrong with these antennas and I have never experienced any RF in the shack with them.
And, in agreement with Cebik, there is certainly no reason why an OCF would have any more gain than a center-fed doublet.
73 de AJ4MJ
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RE: Comparison of Carolina Windom and 186 Foot Lad
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by W6CAW on August 5, 2009
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I put up a full sized, 160M, "Carolina" Windom in January 2008. Have talked all over the world with it. To see the full story go to http://www.craigwilliams.com/radio/shack/index.html
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RE: Comparison of Carolina Windom and 186 Foot Lad
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by K0BG on August 5, 2009
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Let's not assume facts not in evidence.
The first antenna which comes to mind is the magical 43 foot vertical which is seemingly all the rage noways. As pointed out about the OCF, and it's feed point, the length was chosen to minimize the impedance within the various amateur bands. And like the OCF, it does that. You can even work the world with one. Those facts themselves, don't mean much. Both of the antennas require a balun. Without one, a rather large amount of common mode current flow is a given, and may still be present even with a fairly well designed choke balun.
While a balun will help even the lowly resonant dipole, if you're careful about putting one up, you don't need a balun as the CM will be small in comparison to the aforementioned. In this respect, I too agree with Cibek.
Alan, KØBG
www.k0bg.com
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RE: Comparison of Carolina Windom and 186 Foot Ladder Line A
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by W4VR on August 5, 2009
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With the antennas so different in length I believe you're comparing apples to oranges as someone else noted. Also, the two antennas are so close to ground that your results, especially on 80 and 160, are meaningless. When I compare antennas I do it over a period of several weeks to get a good feeling for which one is the real winner.
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RE: Comparison of Carolina Windom and 186 Foot Ladder Line A
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by W9OY on August 5, 2009
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My guess is the common mode is probably responsible for the "superior" performance of the Carolina Windom on the higher bands
Both antennas are quite close to the ground on the lower bands and this will likely overtake any other limiting factor
73 W9OY
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Comparison of Carolina Windom and 186 Foot Ladder Line Anten
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by ZL3AG on August 5, 2009
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Bob,
It seems you have a sizeable piece of realestate to experiment with antennas.
Would love to see the results of comparing the windom with a G5RV.
Thanks for the comparison you have done.
73
Eion
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Comparison of Carolina Windom and 186 Foot Ladder Line Anten
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by KC2SUO on August 6, 2009
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Bob, thanks for posting your experience with these two antennas. I've used both, but not at the same time, so I couldn't do an A/B comparison. Living on a narrow lot, and the location that's most convenient for my mast, I started with a home-brew OCF, Inverted V, with a homebrew 4:1 balun (that I know now was a voltage type) and an "ugly balun" right under the feedpoint. After reading on the 135' doublet I decided to put one up, although the location of my mast prevented me from having the feedpoint at the apex. I really couldn't tell you which antenna worked better, but it seemed the doublet was a bit better, less noise with similar signal strength. I wound up going back to the OCF because I only had a manual tuner and I got tired of always having to tune.
If I understand it correctly, for the same length wire in the same position, the radiation won't be very different. I could be wrong. But the big difference is that the feedpoint impedance will be in about the same ballpark for different bands with the OCF and all over the map with the doublet. On the other hand, the doublet fed with balanced line will exhibit less loss than the coax fed OCF.
I'm still learning and still experimenting. We recently purchased a new house. To say it is a fixer-upper is an extreme understatement. It's pretty much a shell! But I get to customize the radio room the way I want it. And I have more room available outside and I'll probably put up an 80m horizontal loop. So, we'll see how that works, too.
Bill KC2SUO
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Comparison of Carolina Windom and 186 Foot Ladder Line Anten
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by W3ULS on August 6, 2009
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My experience with antennas has been limited to a G5RV and to a "Carolina Windom 80" from RadioWorks. There are lots of reviews of the latter, particularly about the lack of QC. The only thing "Windom" about it is the offcenter fed feature. In other ways, it bears no resemblance to a true "Windom." In my usage I found the commercial "CW-80" to be very good for my purposes at a QTH in VA which provided excellent propagation over the Potomac and Chesapeake Bay to Europe and the Mediterranean. In the good old days of sunspots, I also worked Australia and Japan regularly. (Mostly CW for the latter.)
RadioWorks explains that the CW 80 is NOT a horizontal radiator but instead is designed to radiate vertically from the stub that hangs down from the wire. So the stub has to be elevated if it is to be effective. The wire apparently provides some directionality and support for the vertical radiator, as well as serving as a reverse ground plane. To find the best results at my QTH, I changed the direction by hanging the wire from various trees which surrounded my yard. The best (for me) was a slightly northwest-southeast orientation.
So the above discussion of horizontal radiators does not apply to my experience (now, alas, in the past.) The advantages of the commercial CW-80 were (are) a smooth SWR over 80-10 meters (with a Ten-Tec OMNI VI I could get by easily without a tuner except on the WARC bands), and the ease of a coax feed line. It also outperformed the G5RV (homemade)on all but 20 meters where it was a tie. However, since the CW-80 is only 123 feet or so, its performance dwindles somewhat on 40 and is not much on 80.
What all this adds up to is that what I would consider a satisfactory "Carolina Windom" is not at all what it started out to be in the mind of the inventor/developer. For lazy people like myself, however, the commercial derivative worked quite well.
John, W3ULS
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RE: Comparison of Carolina Windom and 186 Foot Ladder Line A
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by W5DXP on August 6, 2009
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> AJ4MH wrote: And, in agreement with Cebik, there is certainly no reason why an OCF would have any more gain than a center-fed doublet. <
With the same orientation, EZNEC says a 130' OCF has 10 dB gain over a 130' CF in certain directions on 40m. Here are the radiation plots.
http://www.w5dxp.com/dipvwin2.JPG
A 40m A/B comparison of these two antennas could yield extremely different results. Two S-units of gain for the OCF over the CF have been reported on this newsgroup.
--
73, Cecil, w5dxp.com
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RE: Comparison of Carolina Windom and 186 Foot Ladder Line A
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by N7WS on August 9, 2009
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Cecil wrote:
"With the same orientation, EZNEC says a 130' OCF has 10 dB gain over a 130' CF in certain directions on 40m. Here are the radiation plots.
http://www.w5dxp.com/dipvwin2.JPG
A 40m A/B comparison of these two antennas could yield extremely different results. Two S-units of gain for the OCF over the CF have been reported on this newsgroup."
And this can be reordered to say exactly the opposite.
I'm always amused at those who breathlessly claim that a fixed antenna of type XYZ has "gain" over a dipole, without ever mentioning that the "gain" in one direction (often unknown) comes at the expense of signal strength in other directions.
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RE: Comparison of Carolina Windom and 186 Foot Ladder Line A
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by NC2F on August 9, 2009
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I have used an OCF for the last 9 years after several experiments between other long wire designs. My current OCF is the commercially available BuxComm OCF that I recetnly installed. I am still taking notes for comparison, but early indications are I like this design (materials, etc) the best among what I have employed previously.
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Comparison of Carolina Windom and 186 Foot Ladder Line Anten
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by NC5S on August 9, 2009
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Thanks for the comparison.
I'm about two weeks away from building a Carolina Windom and putting it on the air.
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Comparison of Carolina Windom and 186 Foot Ladder Line Anten
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by K9ZY on August 10, 2009
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Bob - Thanks for the time to test and submit the results. I viewed it as a reasonable, and honest, best available scientific approach to field testing. Can I persuade you to try testing your antennas against the W5GI Mystery Antenna? Said to be similar in design to the G5RV, but out-performing it. I see many opinions posted in reviews, but would love to see similar testing as you've done with the W5GI. Many thanks.
Mark
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Comparison of Carolina Windom and 186 Foot Ladder Line Anten
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by KB5YLG on August 10, 2009
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Tri-County Amateur Radio Club of North Texas WC5C had the opprutnity to compare a homebrew OCF dipole with 4:1 balun fed by RG213 with a G5RV fed with about 40ft 450 ohm ladder line set up very similarly to each other, and we've operated with them both about 3 times now when activating Pelican Island and some others. In all cases our results were similar to what you posted, 1 to 2 s units advantage on the OCF, except with a few signals being about equal, even on 20M where one would think the G5RV would perform better the OCF prevailed slightly.
73
David KB5YLG
http://www.wc5c.org
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RE: Comparison of Carolina Windom and 186 Foot Ladder Line A
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by W5DXP on August 11, 2009
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> KB5YLG wrote: ... compare a homebrew OCF dipole with 4:1 balun fed by RG213 with a G5RV fed with about 40ft 450 ohm ladder line ... In all cases our results were similar to what you posted, 1 to 2 s units advantage on the OCF, ... <
Good Grief! It is unfair to bastardize a G5RV and continue to call it a G5RV in order to prove just how bad G5RVs are. A 102 foot dipole fed with 40 feet of 450 ohm ladder-line is *NOT* a G5RV! 40 feet of 450 ohm ladder-line is 1/2 wavelength on 11 MHz, completely outside of the 20m G5RV design frequency specifications.
--
73, Cecil, w5dxp.com
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RE: Comparison of Carolina Windom and 186 Foot Ladder Line A
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by N7WS on August 11, 2009
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Old friend Cecil writes:
"Good Grief! It is unfair to bastardize a G5RV and continue to call it a G5RV in order to prove just how bad G5RVs are. A 102 foot dipole fed with 40 feet of 450 ohm ladder-line is *NOT* a G5RV! 40 feet of 450 ohm ladder-line is 1/2 wavelength on 11 MHz, completely outside of the 20m G5RV design frequency specifications."
Come on Cec, me thinks you doth protest too much. The text right on Figure 2 of Varney's original paper says:
"Convenient length of open wire feeder (preferably an even or odd multiple of quarter wavelength at 14 Mc/S)"
If you want to pick nits and say that 450-ohm line isn't "open wire", then I'll give that to you. Otherwise, I think a "convenient length" includes 40 feet.
Wes N7WS
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RE: Comparison of Carolina Windom and 186 Foot Ladder Line A
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by W5DXP on August 11, 2009
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> N7WS wrote: The text right on Figure 2 of Varney's original paper says: "Convenient length of open wire feeder (preferably an even or odd multiple of quarter wavelength at 14 Mc/S)" <
Hi Wes. Varney later fine-tuned his technical accuracy in "The ARRL Antenna Compendium", Volume. 1, where he defined the G5RV antenna as:
"... a 3/2WL center-fed long-wire antenna on 14 MHz, where the 34 ft open-wire matching section functions as a 1:1 impedance transformer."
Thus an actual G5RV antenna requires a 1:1 impedance transformation on the parallel line for the design frequency. 40 feet of 450 ohm ladder-line is a 1:1 impedance transformer on 11 MHz, not on 14 MHz. A 102 foot dipole is not 3/2WL on 11 MHz. The previously described "G5RV" was indeed a bastard, part 14 MHz and part 11 MHz.
If we accept your logic, one "G5RV" can be a great antenna and another "G5RV" can be non-functional on the same frequency at the same time. Thus the term, "G5RV antenna" becomes meaningless along with any A/B antenna comparisons. Two "G5RV"s could be both 2 S-units better and worse than an OCF at the same time.
Note that Varney's "odd multiple of quarter wavelength" would result in a 50 ohm SWR of ~70:1 on 20m. I'm sure that's why he left such nonsense out of his "ARRL Antenna Compendium" article.
--
73, Cecil, w5dxp.com
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RE: Comparison of Carolina Windom and 186 Foot Ladder Line A
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by WA3LWR on August 12, 2009
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I appreciate all the comments and suggestions. In fact, due to the interest I hope to spend a good month recording data as suggested in hopes of getting more precise data. Both antennas were up at 35-40 foot height, on the two ends of my house, about 40 feet apart. They both had very similar layouts with one wire at 340 degrees and the other at 10 degrees. The Windom's wire slopped down to approximately 20 feet and the long dipole was more of an inverted V by necessity. I have since changed it so that the Windom remains at the height and the long dipole ends will be at 25 feet.
The Windom comes in via 20 feet of RG 8 and the dipole uses 50 feet of 450 Ohm ladder line. Both go to a MFJ tuner.
As I noted, the article was not to say which antenna is better, but to note what I found in a preliminary study of real world conditions and hopes that others would provide their findings too.
I hope to try the one new antenna that was mentioned and perhaps see if I could once again put up a G5RV without putting it too close to the other wires.
Thanks
Bob
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RE: Homework is a good thing.
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by WA3LWR on August 16, 2009
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I am going to try the 135 version after I finish my test results with this longer one, and also make a 160 antenna our of the 186 to see what difference that makes. I then hope to make the super antenna that someone mentioned and reinstall my wire multi band vertical. I figure the more antennas to experiment with this winter the better, and being slightly to moderatly disabled it fills the time.
I wish someone could show me how to use one of the antenna modeling programs so that I could compare results with those.
Take Care
Bob
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RE: Comparison of Carolina Windom and 186 Foot Ladder Line A
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by WA3LWR on August 16, 2009
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In truth, nothing was proven or disproven and that was not my intent. I hoped that others would share their experiences in the real world and that perhaps we could all learn and benefit from the combined experience.
Based on suggestions I have the two antennas at the same height, with their ends coming down to similar heights, and as close to the same angle (horizontal and vertical) as possible and am making a more detailed study for myself. I also expect to construct a few other wire antennas with the ladder line antenna and reinstall my wire multi band vertical, all for comaprisons.
The first time that an apple fell on someone's head they did not realize it was gravity, but maybe after 100000 people had that experience someone did.,
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RE: Comparison of Carolina Windom and 186 Foot Ladder Line A
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by WA3LWR on August 16, 2009
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You mentioned a good point in that the ends being close to the ground could negate the results as far as specific gain. Another person assumed both antennas were inverted Vs and I have enjoyed, long, inverted Vs that were slopping in the last. However, in this case the two vertical peaks have 20 foot poles, and an overall heights of 45 to 50. (I double checked it two days ago) The ends go to one tree at 20 degrees and end at 20 to 25 foot level. The other ends is approximately 260 degrees and at 20 to 30 feet.
I am planning on reinstalling my wire, multi band vertical which would be at 20 feet, and another antenna that was suggested by a commentor and making sure to have a bigger samping.
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RE: Comparison of Carolina Windom and 186 Foot Ladder Line A
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by WA3LWR on August 16, 2009
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I have downloaded the information for the antenna you mentioned and hope to put it up during the next few weeks, weather permitting. This summer has been crazy, very cool (tomorrow may be our first day of 90 or above) we have had a LOT Of rain.
Thanks for suggesting the other antenna.
Bob
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Comparison of Carolina Windom and 186 Foot Ladder Line Anten
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by KB5ZXM on August 17, 2009
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I have a dipole 136 feet long #12 solid wire, fed with 450 ohm ladder line 45 feet long. using 20 foot of rg8 to get it in the window.
the antenna is at 50 feet high . Some folks have called it a double ended Zepp. It runs north and south dead on.
A friend put it up for me, 2 yrs ago. I use a manual AT300 tuner.
The man that put it for me, just bought a Carolina Windom in the mail. He does not like it at all,and He wants to get rid of it and go back to his dipole.
For what its worth, I like dipoles.
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RE: Comparison of Carolina Windom and 186 Foot Ladder Line A
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by W5DXP on August 17, 2009
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> KB5ZXM wrote: I have a dipole 136 feet long #12 solid wire, fed with 450 ohm ladder line 45 feet long. using 20 foot of rg8 to get it in the window. <
On 80m, EZNEC says the SWR on the RG-8 is 57:1.
--
73, Cecil, w5dxp.com
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RE: Comparison of Carolina Windom and 186 Foot Ladder Line A
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by KB5ZXM on August 23, 2009
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Been thinking of coming all the way to the tuner with ladder line, now that I have a non metallic entry panel
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RE: Comparison of Carolina Windom and 186 Foot Ladder Line A
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by W5DXP on August 24, 2009
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When feeding a resonant dipole, one should avoid a 1/4WL length of parallel feedline. Unfortunately, 1/4WL of ladder-line on 80m is about 60 feet, a common popular length for a feedline.
Assume a 50 ohm feedpoint. The SWR for 450 ohm feedline will be 450/50 = 9:1. 1/4WL of feedline will transform the impedance to 9*450 = ~4000 ohms - outside of the matching range of most built-in autotuners.
Increasing the ladder-line length to 1/2WL will solve the problem but that is about 120 feet on 80m.
--
73, Cecil, w5dxp.com
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RE: Comparison of Carolina Windom and 186 Foot Ladder Line A
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by KB5ZXM on August 29, 2009
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I have a manual tuner, with a pair of terminals for balanced line, it is an AT 300. gonna play with this soon. I am in a wheel chair most of the time, so have to wait on my Daughter to come over she's KE5OTM, and her Hubby is KE5OTN.
Will let you know
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