-
You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.
Question on the Vector
- Thread starter The DB
- Start date
One of us only knows CMC does not exist when it conveniently fits into his thoughtless babble. On the other hand when it's convenient to mislead people into thinking the "CMC destroys the pattern as soon as the mast and coax are added", he'll quote W8JI saying just that.
He can't have it both ways and it's not realistic to think this end fed antenna would not have any CMC. What is not apparent until you field test the phase of this radiator is the CMC radiates constructively on the cone as a second current that is shifted by 90 degrees. That's what is causing the unusual pattern CST displays.
I think I've already done what you say here DB in an attempt to confirm the incorrect assumptions W8JI has made in the past about this design. He says adding 4 horizontal radials from the base will improve performance due to CMC.
I did what W8JI said and the gain went down adding 4 horizontal 1/4 wave radials at the base of the cone. As I recall there may have been a very minor change in impedance but nothing to complain about other than the small drop in gain.
I then began to sweep these new radials upwards and toward the cone. When they were close to the cone, the gain returned and the small change in impedance disappeared. I believe this proved there are constructive CMC on the cone and the reduction in gain was due to drawing desired currents off the cone by placing them on the horizontal radials where they do not benefit to this design.
Donald, to an outsider looking in that is what the argument appears to be. I skipped over pages of mindless banter that I really have no interest in reading. I personally think there is another mechanism at play, but that doesn't mean I'm not open to other ideas. That is why that model I created exists, even if I haven't shown it to the public yet, I was testing an idea other than my own. To me an advance in any direction is an advance, even if it completely disproves what I think.
Speaking of what I think, I have my thoughts on what is happening, but as long as this mindless banter continues I really don't wish to jump in the middle of everything. Its like political parties here in the US, its an us vs them attitude, the more polarizes and heated the discussion gets, the more everyone looses.
I think I remember reading something about that experiment you mention, or at least something about what W8JI said. It doesn't sound like what I was thinking of though, although your reports would appear to be evidence supporting common mode currents.
Eddie, perhaps you think this is being over thought. It was an idea I had to test something and see what results we could expect. If the antenna is working the way Donald and Bob thinks it works I had no other real way to see if I could duplicate it with NEC2, and just happened to get a certain amount of gain that matches up with claims that have been around for what, more than a decade now? Based on what I know about modeling in NEC2, not that I claim to know much, the theory behind it appears to be sound. Perhaps I am in error, perhaps not. In time I will learn more and perhaps understand more. Until then I am running with what I know.
If only I had access to a Finite Difference Time Domain software rather than being limited to Method of Moments...
The DB
Speaking of what I think, I have my thoughts on what is happening, but as long as this mindless banter continues I really don't wish to jump in the middle of everything. Its like political parties here in the US, its an us vs them attitude, the more polarizes and heated the discussion gets, the more everyone looses.
I think I remember reading something about that experiment you mention, or at least something about what W8JI said. It doesn't sound like what I was thinking of though, although your reports would appear to be evidence supporting common mode currents.
Eddie, perhaps you think this is being over thought. It was an idea I had to test something and see what results we could expect. If the antenna is working the way Donald and Bob thinks it works I had no other real way to see if I could duplicate it with NEC2, and just happened to get a certain amount of gain that matches up with claims that have been around for what, more than a decade now? Based on what I know about modeling in NEC2, not that I claim to know much, the theory behind it appears to be sound. Perhaps I am in error, perhaps not. In time I will learn more and perhaps understand more. Until then I am running with what I know.
If only I had access to a Finite Difference Time Domain software rather than being limited to Method of Moments...
The DB
DB, If you have an alternate theory of what's going on, I'm more than eager to hear it when you're ready. My only concerns are the new theory should represent the collinear field tests with a 90 degree delay and should explain the odd shaped pattern that I believe CST is showing as a result of the 90 degree offset in two currents on the cone.
I recognize the significance of having to confirm the 90 degree phase delay as functional in the field first and assume you understand how that required phase delay in a collinear version helps us to not only identify the cone is radiating constructively but to also helps identify the odd radiation phase the Sigma forms.
I feel this is a logical conclusion since you can't constructively stack another collinear radiator on top without correctly identifying all of the radiated currents of the existing antenna to predict the required phase shift to drive another section.
I recognize the significance of having to confirm the 90 degree phase delay as functional in the field first and assume you understand how that required phase delay in a collinear version helps us to not only identify the cone is radiating constructively but to also helps identify the odd radiation phase the Sigma forms.
I feel this is a logical conclusion since you can't constructively stack another collinear radiator on top without correctly identifying all of the radiated currents of the existing antenna to predict the required phase shift to drive another section.
Well I'm disappointed guys. I went out to dinner with my family and I figured you guys would be ganging up on me hot and heavy. But I get home and every thing is quite on the Vector front. Were you just catching your breath after the whirl- wind I gave y'all today.
Since you guys have me in a corner now...with this new modeling idea...I figured you would be buzzing with chatter and likin' your lips. We got Old Grampa on the run now.
DB, if your model is correct, then this is a whole new ball game. Do you think your model is correctly showing us 6+ dbi gain? I've only been able to get my best S4 model to show about 4.06 dbi over real Earth and my Vector 4K shows a little less than the S4. We have compared other model results before, and I was thinking that we were always pretty close on the gain.
What do you mean when you say "...another mechanism at play...?" Does that mean something else is going on with the model, or something else is going on with this antenna? I'm just curious.
Can you describe how and what you did with adding the extra wires? How far are they from the other wires? I guess you made the new wires along side of the radials, right? I'm asking, because even though you fixed it OK, earlier you messed up reporting the high average gain value you got, and that threw me off. Are you sure you checked your model real close, and there is not something else going on that you don't realize yet? I'm trying to be helpful.
I look forward to your showing us some of you model reports.
Let's put it this way DB, I still have my doubts, but I'm really paying attention, now that you guys have me in a corner with this new info. Do you think I'm out of the box now, or am I still in the box, or was I never in the box?
It looks like the idea of your adding wires was all that maybe made the big difference. I guess Bob came up with that idea, when we talked about currents last week and I posted the part about currents from the Eznec manual. I guess he was thinking outside the box when he read that.
Do you really think this also means that Donald was wrong after all, and that NEC2 can model the S4 design correctly, and that your adding those extra wires made all the difference? What did your model show for gain before you modified it with Bob's idea?
Good luck,
Since you guys have me in a corner now...with this new modeling idea...I figured you would be buzzing with chatter and likin' your lips. We got Old Grampa on the run now.
DB, if your model is correct, then this is a whole new ball game. Do you think your model is correctly showing us 6+ dbi gain? I've only been able to get my best S4 model to show about 4.06 dbi over real Earth and my Vector 4K shows a little less than the S4. We have compared other model results before, and I was thinking that we were always pretty close on the gain.
What do you mean when you say "...another mechanism at play...?" Does that mean something else is going on with the model, or something else is going on with this antenna? I'm just curious.
Can you describe how and what you did with adding the extra wires? How far are they from the other wires? I guess you made the new wires along side of the radials, right? I'm asking, because even though you fixed it OK, earlier you messed up reporting the high average gain value you got, and that threw me off. Are you sure you checked your model real close, and there is not something else going on that you don't realize yet? I'm trying to be helpful.
I look forward to your showing us some of you model reports.
Let's put it this way DB, I still have my doubts, but I'm really paying attention, now that you guys have me in a corner with this new info. Do you think I'm out of the box now, or am I still in the box, or was I never in the box?
It looks like the idea of your adding wires was all that maybe made the big difference. I guess Bob came up with that idea, when we talked about currents last week and I posted the part about currents from the Eznec manual. I guess he was thinking outside the box when he read that.
Do you really think this also means that Donald was wrong after all, and that NEC2 can model the S4 design correctly, and that your adding those extra wires made all the difference? What did your model show for gain before you modified it with Bob's idea?
Good luck,
Last edited:
That was a great attempt to make something look appear different than reality. Don't you mean to ask DB "do you really think that means Donald was right all along when claiming every model in EZNEC we have seen before failed to properly identify the cones radiation"? "Does that mean Donald was right when he said all of the EZNEC models we have seen failed to show gain that is present from the cone and produced errors with phase?
Maybe he's just delighted that a few times in frustration I have said EZNEC was useless in modeling this antenna and now with the extra wires you're getting new results? I concede, him and Cebik may be right here and it's just so difficult DB is the first one to recognize EZNEC needs extra wires to do what CST does with this antenna.
Now if only Marconi could connect that in some way that would make the models he's been providing all his opinions on be accurate. I hope DB is on track so he can show you why all the old EZNEC models failed to show the gain and phase of the Sigma in the field.
this is funny,
"It looks like the idea of your adding wires was all that maybe made the big difference. I guess Bob came up with that idea, when we talked about currents last week and I posted the part about currents from the Eznec manual. I guess he was thinking outside the box when he read that"
stop guessing & patting yourself on the back eddie,
the extra wire is nothing at all to do with you posting the eznec instructions,
i found that feedline info over 12 months ago from amateur forums and posted links,
i don't know the answer myself so i asked if eznec would show cmc flowing on the outside of a transmission-line when the transmission-line was part of the antenna becase it does not when modelling coax unless you add an extra wire to simulate the outside of the coax
you could not answer with any degree of confidence so you posted the EZNEC instructions,
dementia is a terrible thing eddie, it creeps up on you getting worse month by month,
sufferers don't realise what's going on other than they don't remembering things like they used to years ago,
to people around sufferers its obvious what they do think they remember they get all twisted and confused, they know somethings up with grandpa,
i hope you enjoyed your dinner.
"It looks like the idea of your adding wires was all that maybe made the big difference. I guess Bob came up with that idea, when we talked about currents last week and I posted the part about currents from the Eznec manual. I guess he was thinking outside the box when he read that"
stop guessing & patting yourself on the back eddie,
the extra wire is nothing at all to do with you posting the eznec instructions,
i found that feedline info over 12 months ago from amateur forums and posted links,
i don't know the answer myself so i asked if eznec would show cmc flowing on the outside of a transmission-line when the transmission-line was part of the antenna becase it does not when modelling coax unless you add an extra wire to simulate the outside of the coax
you could not answer with any degree of confidence so you posted the EZNEC instructions,
dementia is a terrible thing eddie, it creeps up on you getting worse month by month,
sufferers don't realise what's going on other than they don't remembering things like they used to years ago,
to people around sufferers its obvious what they do think they remember they get all twisted and confused, they know somethings up with grandpa,
i hope you enjoyed your dinner.
With all due respect, I have been critical of both sides. If anything I'm the one who has been drawn kicking and screaming into this argument that my previous posts clearly shows my views on. My name was brought up by not one, but both sides.
The model was a proof of concept, nothing more. It does match the gain figure that has been talked about, but its dimensions don't match the actual antenna, not really even close. Its vertical element is .92 wavelengths long, and if you change that length in either direction the gain drops. The radials are also shorter than the Vector model. I'm not saying it is a perfect model, only that the theory behind its creation is sound.
I've talked about this other mechanism on these forums several times, including earlier in this very thread. Its not an easy concept to try and explain, unfortunately. And I think something else is going on with the antenna as a whole.
I'll post the .nec file for anyone who wants to play with it. I'm not sure if that can be imported into EZNEC directly or not.
We guys? I addresses that above. When it comes to thinking outside the box, I have spent much time in troubleshooting and repair. To be successful in that type of field you need to know how to think outside the box. I am comfortable trying out different ideas, and I notice things that most choose to ignore. I'm a thinker, and am thinking constantly. I can't tell if you are in our out of a box at the moment however, I can't physically see you or the space around you... I also can't see if you are in a corner...
The discussion was had and the model created before that conversation on EZNEC ever happened. Bob and I came up with the implementation separately, although I think the implementations we had in mind are very similar.
According to Donalds four wire test, NEC2 still hasn't accurately modeled the Vector design. That four wire test is something I am questioning, and hope at some point to actually put it to the test. Note the word hope, I have never once given my word or promise that it would be done. That being said, I am curious, and that can be a dangerous thing... In any case, it will be a while before I can do any such test anyway.
Link to the .nec file (.txt extension added to get the web server to allow the file to be shared).
The DB
I took a look at an idea and an observation that was mentioned earlier, and that is the appearance of a 1/2 wavelength radiation pattern on a 1/4 wavelength section of antenna. I do kindof see it as well, however the operative word is kindof.
Anyway, the possible explanation given by Donald (I think it was him) thinking it was due to the interaction of multiple currents combining on the basket radials. This idea can be tested, rather easily actually, using a simple spread sheet and its charting feature.
What I did is create a sine wave on a chart in the spreadsheet by having the spreadsheet calculate the sine of every degree from 0 to 360. I then created a second sine wave that was, in the examples below 90 degrees out of phase. It created a chart that looks like this:
Lets say for this purpose that this represents the current strength and phase of two separate sine waves that are not in phase on a single antenna element. When multiple currents exist from separate signals on a single wire at any given point the currents add. Because of this I added the currents present in every degree of both sine waves and this is what I got:
We get a new sine wave that has the same frequency as the others. The amplitude of the currents of this new sine wave is dependent on the phase relationship of the sine waves that created it. The closer their phase relationship the stronger the amplitude of the new sine wave. However and critically, the frequency does not change. I did this same test with varying phases and predictable results.
I did the same test with three four and five sign waves and adding them all together, the results are the same, a single sine wave with the same frequency results, so no matter what you do as long as the frequencies being considered are all the same you get a result of only that frequency. Therefore according to this test the 1/2 wavelength pattern on 1/4 wavelength of antenna simply cannot be... However...
However, after some thinking I have discovered that this test has a critical flaw that changes everything. Can anyone guess what that flaw is? I'll give you a hint, it is in the writings (at least the books) of M. Walter Maxwell...
The DB
Anyway, the possible explanation given by Donald (I think it was him) thinking it was due to the interaction of multiple currents combining on the basket radials. This idea can be tested, rather easily actually, using a simple spread sheet and its charting feature.
What I did is create a sine wave on a chart in the spreadsheet by having the spreadsheet calculate the sine of every degree from 0 to 360. I then created a second sine wave that was, in the examples below 90 degrees out of phase. It created a chart that looks like this:
Lets say for this purpose that this represents the current strength and phase of two separate sine waves that are not in phase on a single antenna element. When multiple currents exist from separate signals on a single wire at any given point the currents add. Because of this I added the currents present in every degree of both sine waves and this is what I got:
We get a new sine wave that has the same frequency as the others. The amplitude of the currents of this new sine wave is dependent on the phase relationship of the sine waves that created it. The closer their phase relationship the stronger the amplitude of the new sine wave. However and critically, the frequency does not change. I did this same test with varying phases and predictable results.
I did the same test with three four and five sign waves and adding them all together, the results are the same, a single sine wave with the same frequency results, so no matter what you do as long as the frequencies being considered are all the same you get a result of only that frequency. Therefore according to this test the 1/2 wavelength pattern on 1/4 wavelength of antenna simply cannot be... However...
However, after some thinking I have discovered that this test has a critical flaw that changes everything. Can anyone guess what that flaw is? I'll give you a hint, it is in the writings (at least the books) of M. Walter Maxwell...
The DB
I may have over simplified my analogy with any two waveforms combining since all 1/4 wave radiators start with maximum current at the source and always go to minimum at the far end. Now what happens if we put two currents on the same 1/4 wave BUT their sources are at opposite ends of that 1/4 wave radiator?
Is it not possible for both ends of that radiator to come to a current minimum since each is an end for one current? As we reach both ends of the radiator, the phase shift between both currents might just be nulling the currents out at the ends. It is the only logical explanation I can arrive at for what we see although, I'm all ears if there is another plausible theory.
Thanks DB, I'll try and upload this to Eznec. Is this your model before you modified it with the extra wires?
I know that Bob and Donald are excited about your new information that might help explain to us how the S4 design might work, but you must remain objective and don't go being subjective on us.
I appreciate your being objective here and having questions, I'm sure both Donald and Bob would agree.
I know that Bob and Donald are excited about your new information that might help explain to us how the S4 design might work, but you must remain objective and don't go being subjective on us.
I appreciate your being objective here and having questions, I'm sure both Donald and Bob would agree.
DB, I see you doing a lot of other work trying to justify what we see in your report, but you have an error in your application, and it is not so obvious to show some glaring results...except you see a gain that is too high for this antenna. At this point it is easy to become subjective.
If you check and recheck your model you might find out something is going on that you don't realize yet. I think you know the problem if you see it, but all of this other stuff...that might come into question later, is right now a distraction.
If you check and recheck your model you might find out something is going on that you don't realize yet. I think you know the problem if you see it, but all of this other stuff...that might come into question later, is right now a distraction.
Well, bonus points awarded, the first paragraph nailed what I was looking for. What happens if two signals (or sign waves) of the same frequency are traveling in opposite directions on the same medium. A coax environment is where such an occurrence exists in an antenna system, and in that case they create a waveform that has 180 degrees of phase shift in 90 electrical degrees of coax. Unfortunately the case here isn't exactly the same as a coax, and I'm not sure (at least yet) how to properly chart it.
In this case I have an idea of what would happen, and I may be stretching something to its limits or even beyond here. Take a look at the charts I posted in my previous post, namely the second one that includes the blue, red, and yellow lines. If you look at the 1/4 wavelength of the yellow line between the peaks of the blue and red lines, what do you see?
The DB
DB, Interestingly enough, I tried to model my idea in EZNEC and I see some results. Turns out if you make a single 1/4 wave element and apply a source at BOTH ends, you'll get something very close to that odd shaped 1/2 wave pattern over a 1/4 wave radiator just like I expected. Not sure why I didn't think of this idea before.