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The 5/8-Wavelength Antenna Mystique by Donald K. Reynolds

Discussion in 'CB Antennas' started by Marconi, Aug 9, 2011.

  1. Marconi

    Marconi Supporting Member

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    For some years now I've made claims based on the following article I found in ARRL's Antenna Compendium Volume I, page 101-106, published in 1985, by Donald K. Reynolds, see his credits in his obituary: Obituaries | Donald K. Reynolds, Professor, Engineer, Musician, Storyteller | Seattle Times Newspaper.

    This review article was based on studies by RF Engineering notables in the early 20's-30's. These engineers were charged with doing RF studies for the newly developing US Broadcast Radio Industry of the times, and this fact is noted in Reynold's review. The principals involved in these theoretical studies are listed and captioned at the end of this article. You can go to this article in this periodical by selecting page 101 in the task field at the bottom of the page and clicking the enter key.

    6769788 the ARRL Antenna Compendium Vol

    I have also referred to another article about the same time that discussed Japanese RF Engineers refuting the 5/8 wave idea...as being wrong and that the vertical .64 wavelength monopole would show the most gain under the guidelines set forth in the US study. Reynold's review does mention the US study for Broadcast Radio, but mentions nothing about the Japanese idea I remember reading. Maybe one day I'll locate this Japanese report and maybe even be able to understand why the .64 wl idea never took much of hold in the US, excepting maybe in CB.

    BTW, the idea of .64 wavelength radiator is not totally absent in the armature radio antenna world, and its lack of seeming popularity is not meant to be suggested in this work either. The very popular Extended Double Zepp is noted to be a .64 wavelength antenna, so the idea for this particular length radiator as being new or an idea developed by the Japanese is not true either...or suggested by me. A little history for the Zepp: G3ZPS HF radio antennas



    The point of this post is to again try and shed some light on the subject of real world vertical antenna gain and the affects of Earth on the patterns vs. the theoretical ideas presented in these reports for Broadcast Radio from the 1920-1930's.

    IMO this topic of 5/8 and .64 wave antennas are discussed a lot in CB circles, and the source may well have been taken from these very reports. However, I contend that if you read very closely you will see the errors in the common CB thinking on this subject, and it may change you mind a bit about real antenna gain, and how theory and real world results may not be at odds as many seem to think.
     
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  2. Marconi

    Marconi Supporting Member

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    Here is a similar report by Cebik W4RNL

    Here is another report done by L. B. Cebik, W4RNL, with additional information relative to antenna height and soil conditions for the 1/4 and 5/8 wave radiator.

    This report also suggest similar results as noted in Reynolds report posted above in this thread.

    If you read this one closely you might be surprised at how Earth affects these vertical antennas, I know I was.

    In this report, Cebik gives us the modeling data and dimensions he used, so I decided to see how my models compared with his work. Well, I was surprised as to how close my models were to his in pattern, angle, gain, and feed point match.

    After I tweaked my models to simulate his models more closely, the results were almost identical in every case I tested. I have attached an overlay for two of my model for a 5/8 wavelength with slanted radials vs. horizontal, at 25' in height, over very poor soil conditions, using Cebik's dimensions. You can compare my results to his images at the bottom of page 9 of 12 posted below or in the report.

    I'll note here, that we hear a lot of hoop-la made by some that comes for Cebik's own commentary regarding modeling and its limitations, but the modeling he does in this particular report all seem to violate his own warnings, so-to-speak. So, this gives me some confidence that my models are not necessarily as far-fetched as some would have us believe.

    These are 5/8 wave models with slanted down radials vs. horizontal radials.
    View attachment Cebik's models simulated.pdf

    I tried to post the full report, but WWRF refused me permission. Maybe my file was too large. Here is the link to this report: http://www.cebik.com/content/gp/58-3.html, but I think you'll need to log-on or register to the Cebik's Website in order to see it.

    View attachment Cebik's report pp 9 of 12..pdf
     
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    Last edited: Aug 11, 2011
  3. jazzsinger

    jazzsinger Bullshit Buster

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    Would be interesting to see how the modelling would show a 5/8 wave with slanted upward radials at various angles as well as horizontal and downward sloping ones, would give a more complete picture if the aim is to see the effect radial design has on gain/toa.

    repeated over different ground types would clarify the picture further as would repeating it with a 1/4 wave gp with radials at different angles.
     
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  4. Marconi

    Marconi Supporting Member

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    George, I have not tried making a 5/8 wave long radiator with radials that are raised up like the Sigma4. It may be a good idea, but based on what we know happens with the S4 compared to a 3/4 wave GP with horizontal radials, what do you suspect will happen to the 5/8 wave...regarding gain, angle, and pattern?

    I have made my S4 model, that I have set to the Antenna Specialists specs a bit shorter before, and I found it improved the gain just a tad. I will try doing what you suggest later today. Maybe I'll try the same with a 1/4 wave also.

    What did you think of Cebik's article on the 5/8 Wave Mystique? Did you really read it or just look at the pictures?
     
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    Last edited: Aug 12, 2011
  5. bob85

    bob85 Supporting Member

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    jazz,
    eddie is recapping what we have gone over before, i posted about cebiks 5/8wave mystique and upper hf monopoles a long time back, theres nothing new in either article unless you forgot its been discussed before more than once on here on paltalk and via email,
    i recall we talked about eddies very good texas soil vs jay's very poor soil as a possible reason jay sees his 5/8wave perform so much better than other antennas and eddie sees little difference between any of his antennas in their respective antenna tests, i also talked about what cebik had to say about it in his "some poorly grounded speculation" that warranted further investigation at the end of his upper hf monopole article radial angle was also talked about,
    i don't recall any hoopla or cebik giving any warnings about simpleton groundplanes, it is w8ji that warns about modelling without a mast/feedline, cebik only said that modelling the sigma style antenna and getting accurate results would be difficult, i posted the other things he said in the sigma4 an alternative view post,

    the sigma model does not fit what we see in every test we do here, what cebik and the patent said about them does,
    a week or so ago another local swapped his beloved a99 for a beat up old snapped vector 4000 measuring less than 27ft with 90" radial sleeve, after some over the air instructions on tuning the shortened due to breakage vector his signal increased 1-unit on my icom and more on the ft847 and some cb's, he talks/hears significantly better than ever before to everybody, how do you reconcile that or the many other tests with the same result that been a notable advantage in favour of the vector with the nec models or tests presented here ?,

    i don't know how we are supposed to follow eddies test charts when even eddie has changed his mind more than once about which antenna performs best as he goes over his charted test results, at one time it was the a99 then the sigma4 now its the gainmaster or is it the starduster but only if its got 6 radials and equal tip height or maybe its the new top-one but only if its not next to the tree in the yard its above the house roof and the ducks are at the far side of the pond in the local park,

    we can see and hear in eddies excellant videos what happens when you test antennas two at a time using an antenna switch on ssb mode with changing conditions using stations that have no interest in antennas,
    you capture the effects of changing conditions / antennas been in two different places and the possible effects of inconsistant transmitter output from people often unaware any test is been done, the videos are a fine example of how not to test antennas,
    its unfortunate that eddie can't enthuse his locals to participate with interest, its not like that here, i have no problem at all collecting a handfull of stations and taking them to a ch for antenna tests, plenty of people are interested and will take time to assist, others will join in without asking,


    i commend eddies hard work in demonstrating to people who have not been testing antennas against each other for 30+ years the potential pitfalls of do it your way antenna testing,
    without the two antennas on a switch average joe would probably never realise that changing conditions/positions screw up your test:)

    I'll note here, you need a good memory if your gonna play forum smartass(y)
     
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  6. HomerBB

    HomerBB Well-Known Member

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    Have Mercy!!! :eek:
     
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  7. Marconi

    Marconi Supporting Member

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    No Bob, recapping our old business was not what I was intending to convey in this thread…at least in my thinking.

    The other day I was considering your old thread “5/8wave vs .64wave”, so I Googled “5/8 wave antennas” to see if there was anything new in this regard. It had been a long time since you asked your question, so I posted a question asking if anybody had found such a link that might possibly give us some answers. So I went checking.

    I opened a site near the top of the Google list of related topics. It included the entire issue of “ARRL Antenna Compendium Volume 1,” published back in the 80’s. Here was an old issue of an old review that has interested me for years, because it seemed to support some of my real world testing results and ideas.

    This article was entitled “The 5/8-Wavelength Antenna Mystique” by Donald Reynolds. Over time I had used excerpts and images from this review as a references…trying vainly in most cases to support my words and ideas in discussions on these forums. Up until now, I was never able to provide the full text so that others could read and study it fully. This is when and why I decided to make my post, and IMO it had little to do with our old business or our having discussed it before.

    This review was not the actual report on the subject of the 5/8 wave radiator that I have also been looking for since gaining access to the Internet, but it did consider that particular work done back in the 1920’s, and underwritten for US Broadcast Radio industry developing at the time.

    For some time it has been my belief that this review might be the bases for what I considered… possible erroneous thinking regarding real world antenna gain and in particular as generally commented on by CB operators. I couldn’t prove anything, but again, what I read in that review seemed to support the real world experiences that I had been seeing for some time. Maybe this part might touch on our old business, but for me I was thinking, finely, if forum members could actually read this review in total, it might help explain some issues that I have been suggesting for years.

    In this process of my search for new info on the 5/8 wave I noticed another old article that Cebik had written, with a similar title. This too might be some of that old business you mention. However when I read it this time, with a little modeling experience under my belt, I viewed its contents in an entirely new way. As you suggested to me a while back, while I was lamenting about my not getting much help with my modeling efforts, you suggested that I look for some modeling examples on the Internet and in books. In doing so, I found that most examples, as such, did not provide enough detail about the models as presented...for my purpose in figuring out if I was on the right track with my own modeling efforts.

    Well, in reading Cebik’s work again, I noticed modeling details that I had previously just glazed over…due to a lack of any understanding with Eznec. Here finally, I saw details that seemed to be enough for me to use in trying to duplicate Cebik’s work. So, if I was lucky maybe I could gain some needed confidence that I was either on the right track with my modeling efforts, or that I was close, or worse yet...that I was way off base completely. So, you see Bob, in my mind I wasn’t really trying to recap some old business. I also think you can glean a little of my thinking, based on what I posted to George in a previous post.

    Maybe I got carried away a little…trying to explain my idea for this thread and create a little interest so that others might actually read the links. I didn’t figure many would take the time to read for understanding, but if someone did devote some quality time and had a different viewpoint, then maybe they would come forward with their ideas. Maybe I would discover something new and/or change my mind…similar to what has happened to me in numerous conversations between you and I. There is no one on these forums that has provided me better understanding on issues than you, whether we agree or not.



    Generally, I do recall such conversations, and Earth affects do interest me of course, but this was not what I had in mind here. Cebik did do us a big favor by including this aspect…regarding gain and angle over different types of soil however.



    Maybe this was a bad choice of words, but I was trying to stimulate some interest. Usually I would suggest that a controversy always seems to do that best among humans.



    Regardless of what I might have said in the past, I think my Sigma4 is probably the best antenna I have and for sure when all antennas are mounted on the same mast. To be honest I have not tested my pride and joy enough, because of my fears for weather taking it out. In addition I suspect, based on my recent installation of some other antennas, and not securing them well, that an antenna that is loose at any point is likely to produce some form of unreliable results. Did I ever install my Sigma 4 correctly, YES for a time!

    Only recently did I become aware that I possibly had such a problem, and how it might have affected performance. My notes do not give me enough information to tell what the situation was when I had the Sigma4 mounted in previous test. As noted, I only discovered this recently while mounting one of my Stardusters and with my New Top One at some point. At some point in time I have noticed this same problem with my old Top One too.

    Due to the last 3 months of heavy winds and heat, I have not been able to test such ideas and check out my Sigma4. The last antenna that I had up that showed such a problem is my Starduster. I have it up now at 55’ feet to the tip, and installed better. It is working fine as best I can tell. It responds very well compared to the Gain Master at 61’ feet to the tip…with a slight edge to the Gain Master.

    I agree that testing side by side arguably has issues, I made mistakes in reading signals at times using sb mode, I had some installation issues, I tested at different heights for the test models, and I made averaging mistakes in some of my recaps as I note below.

    I did have a recap that showed my A99 being among a group of other antennas with the highest average signals. I think I tried to explain that at some point, but maybe I didn’t actually post that conclusion. I know that I talked about it however when I lost several of my regular contacts in the regular test group. In fact it was that test period where the A99 showed to perform so well…where I later discovered such mistakes in averaging my signals. The mix of weaker and stronger stations changed as a result and I tested the A99 a lot more that other antennas. Sometimes stuff just happens.

    Bob, you know my memory is poor, so you can’t be referring to me.
     
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    Last edited: Aug 13, 2011
  8. bob85

    bob85 Supporting Member

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    we can all make a bad choice of words from time to time eddie, its better to harvest the honey rather than poke the hive with a stick,

    i tend to believe the ground can play a notable role in the equation unless you are high above ground.
     
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  9. Marconi

    Marconi Supporting Member

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    Well I'm back to the question Bob asked.

    I was successful in duplicating the modeling dimensions that Cebik used for his .625 wave with horizontal GP radials, at 25' feet, over Very Poor soil.

    I figure if any models were correct, it would be Cebik's models. I checked this one to all the soil conditions he tested in his report noted above and the numbers for gain, angle, lobe #, and the feed point impedance were all surprisingly the same.

    I then added 6.2" to bring his .625 wave model to .64 wave and here is the following output I compared. I also did a pattern overlay for both models as noted on the first sheet in my supporting images. Note that the .625 is ahead in gain by a modest amount while the .64 shows a modest advantage in the match.

    View attachment Bob's question .64 vs, .625.pdf
     
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  10. Needle Bender

    Needle Bender Well-Known Member

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    why are the ground planes nine inches shorter than a 1/4 wave? can you elevate the radilas like the new penetrater and see if that changes anything?
     
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  11. Marconi

    Marconi Supporting Member

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    I'm glad you asked NB, because I don't understand it either. My models were set to the measurements that Cebik noted in his report and they also seem to go against the radiator/radial length ratio of 5%, a rule we often read about.

    I used his models instead my own to give my basic point of view to Bob's question regarding the .64 wave vs. 5/8 wave, just in case some questioned my modeling skills. I can't argue the point that Cebik's dimensions are wrong, because my versions of his models show better results than my own do.

    In the process of trying to figure out what he did and get these models to show exactly the same matching and gain results as Cebik, I had to tweak the segment counts, which he didn't provide. He used about twice as many segments as I would have, and that is the only difference that I found.

    His measurements are a bit shorter all the way around than my model for a similar wavelength and frequency...using my notions for the math. I would have tended to make the 5/8 wave radiator for 28.500 mhz about 258.8" and the radials close to 105", more or less, but he must be right, because his results are a little better than my own models.

    When the new Penetrator came out I tried to model the idea of raised radials, but I wasn't successful in figuring out the bracket. For years my thinking was the 500 design may have some advantage in performance due to their raised ground plane. I never owned one, but have heard a lot of reports about how good they are, but it was nothing but CB talk. Nobody's reviewed their new 500 yet, so I decided to wait before getting back to the model.

    I tried to physically measure the current in the radials for my I-10K using a MFJ854 and a standard electrician's clamp on amp meter, but never detected anything. Maybe the current was just too small. You'll note that Cebik may have alluded to this lack of current flow issue in 5/8 wave antennas in his report, when he talked about the current standard he used on the 1/4 wave antenna without a word in this regard for the 5/8 wave. I'm assuming here, but sometimes you have to read between the lines. It is also possible his standard idea does not apply to 5/8 waves. My modeling also shows these 5/8 wave antennas with very little current flowing in the radials and you can see some indications of that in the images above.
     
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    Last edited: Aug 17, 2011
  12. Needle Bender

    Needle Bender Well-Known Member

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    isn't the current highest about 1/4 wave down from the top?
     
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  13. Marconi

    Marconi Supporting Member

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    I believe you're right.
     
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  14. Needle Bender

    Needle Bender Well-Known Member

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    had to happen sooner or later;)
     
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  15. since the merlin base antenna and most mobile antennas are less than 7 ft tall above their feed-point ...... does that mean the current is highest 2 feet (or lower on shorter verticals) below the feed-point on the ground planes or car body ?
    does it mean when my 3 ft lil will in on the 6 ft high roof on my vehicle that the current is highest just under the tires ? if it were on a trunk , would it be 3 ft under ground ?
     
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