i think i understand what your model shows eddie,
i don't dispute the original was too long with the 90" sleeve, the 5/8 j-pole models also show worse performance than a conventional j-pole, even the 5/8 super-j,
i won't be shortening my sigma to exactly 3/4wave until im ready to lose a little signal im my yard, i can't explain why that is at the moment,
with regards to nec,
i would like to understand how it sees the cone,
I'm going to have to assume you're referring to the two reports I posted several days ago regarding extending the lengths of the S4, that I did in 2/12, over real Earth, and a 3/4 wave without a hoop in FS that I just did a few days ago, right?
Bob, just like my advice to Donald regarding his production products, I would not change anything he's done concerning his business based on anything these Eznec models I make...that I use strictly to try and demonstrate my thinking.
These models only purpose for me is to try and get some idea for how antennas might work. I see something similar to what you guys see in Donald's animation, but I describe it entirely different. As a result, I see a difference in results only...using my idea for the theory of cancellation as it applies to the cone of this design and that difference that remains in phase with the top 1/2 wave radiator is very small...compared to the significant in phase RF that Donald is suggesting. And I don't see any CMC development at the top hoop of the radials either. I see only a current node up there, and that is the very antithesis of a point where CMC could be generated. Plus Donald told me the other day in response to a question I asked in a post I made, He stated that CMC's starts at the bottom of the radials...at the coaxial feed point as the coax is terminated into the elements. This is why I no longer believe that BS that freecell preached a long time ago that the cone was an extension of the coax. That said, I believe it and I parroted it at the time.
Again what I do on the forum is opinion and some practical, not scientific, application of hands on experience, just like you've done Bob...in the past too.
I see a similar bases for your opinion Bob as I do for my self. Donald has his real world production, sales, customer satisfaction, and more importantly his antenna testing...which rightfully we will never see any evidence for, so with Donald we have to have faith in his word alone about that part of his ideas when he says what he says in that regard. I refuse to ask him any questions about his testing out of respect for his business and his obvious need for some security in that regard. So I don't consider his words on the matter when he tells us about his testing results.
On the other hand I not only try and describe much of what I've done using notes and other exhibits, but I've also done many videos that tend to show everything I do, and you guys are fee to pick-apart all of that.
Bob, you and Donald only give us, for the most part, words and sometimes you reference long and wordy reports where you glean information, and that is fine, but sometimes I never see or imagine what you had in your minds eye...without just guessing even after spending time going over the references you do provide.
Models should only predict what a real world antenna might do and that is never enough in every situation. Real world testing and experiences are king, and that is why you, I, and Donald probably try our ideas out in the real world...just to see if we can glean anything worth noting.
I am amazed that you both have so much faith in Sirio's singular source of information about the NV4 antenna, the animation, when on the other hand Sirio plainly publishes their New Sirio Vector 4000 as coaxial J-Pole.
But, more importantly you and Donald both claim using a radiator that is much longer is best in your experience and I have no reason to doubt what you report. But with that said, and in spite of Sirio's professional experience, team work, and their use of CST...they still build the NV4 to almost precisely 3/4 wavelength...even after designing it using CST. What does that tell us?
These are two facts that you both bitterly disagree with in principal just for starters, but when all is said a done...neither of you can justifiably explain this real world dichotomy, relative to though and ideas regarding how this antenna design works. I can say I don't have to try and overcome the obvious when others note these issues that are out there in the light of day.
I have no real problem with anybodies opinion...even though I might disagree, but some folks around here are suggesting to shut off opposing opinions...that don't agree with there own.
That is flat out not right.
I've said it before, if all we have is to get personal then I don't consider our arguments worth considering at all.
At best, however, I would never forget what I've done in the past, and this is why I make and keep notes. But, I would never confine my thinking by not considering new information or ideas of others. Maybe redoing some old experimentation just to see if I can duplicate my old findings, along with something new if it seemed reasonable.
with regards to nec, i would like to understand how it sees the cone, if eznec has no function for radiation from transmission-lines with cmc unless they are two wire balanced lines with an unbalanced load which can be modeled as two parallel wires like a j-pole,
how will the mathematical model built into eznec include any common mode there may be on the outside of the 4 radials which looks to me like what cst shows?
I don't read page 83, section on "Modeling Coaxial Cable," as you suggest here Bob. And rather than just leave my comment at that, like you tend to do with me, I'll explain exactly why. The text says more or less,
"A radiating coax cable can be modeled quite well with a combination of transmission line model and the added wire, where the TL serves as the center conductor and the added line serves as the outer shield." This is where we understand CMC's tend to flow, continued........
This is also noted in the text and is why it is important to make the 3rd wire that serves as the shield...the same size as the coax shield, else there will likely be some difference to be noted.
with regards to nec, i would like to understand how it sees the cone,
I report what I think I see, but I depend to some extent on my analysis of the currents log that Eznec produces. This is why I post and try and explain the currents log and it is also why I think we'll likely never know for sure what the CST animation really means to understanding the currents noted. I relegated the idea of understanding the details of the CST animation to asking 100 folks their opinion of a
Rorschach test image the other day.
I still have questions about Eznec's currents that I cannot answer, and I've talked about currents many times, but few are willing to stick-their-neck-out to even discuss the issue. I'm trying to understand something new for me, and it is called currents. Currents are not an easy subject for me, and again few want to even discuss a word on the subject.
So, my ideas are just as valid as your's, and all the others on the subject unless we are following Gestapo like tacts.
Donald will tell you that even Roy Lewallen is not willing to discuss the matter of currents, and I sorta understand why. So Bob, you and I are both just guessing.
i can see it working with a regular j-pole evidenced by cebik's j-pole article which is a balanced line feeding a 1/2wave radiator, and plenty more j articles,
Bob, there you go again. I'm not sure exactly what "it" means in your statement here. Using the word "it" in the context of details subjects is to me a cop-out, that leaves wiggle room to claim others just misunderstand when the rubber hit the road. You're adamantly against considering the S4/NV4 being a J-pole, yet you tend to come back to using the J-Pole to help support your arguments somehow. I'm not saying ideas we hear about J-Poles are not important to the subject of understanding the S4/NV4, but again we are left to possible misunderstanding with just the mention of the word J-Pole just being put out there.
so what happens when you make it an unbalanced situation by adding the extra radials, does it then ignore any cm radiation from the lower 1/4wave in its gain and pattern calculations, making the model a 1/2wave elevated 1/4wave higher above ground?
Here we see a difference of opinion again. I believe you're talking about a J-Pole here again, right?
I don't see adding extra radials to a J-Pole making an unbalance situation, like getting worse. IMO, when we add extra radials to such a setup like the J-Pole we should see balance improve.
Am I wrong or did I just miss something here?
sirio claim the same 4.15Dbi gain for all their 3/4wave sleeve antennas,
I see that too, and I've asked Sirio for a fuller explanation of exactly what ground condition those values were calculated over...as in Real Earth or Free Space. They never answered my email contact, and they use a proprietary email system that leaves no trace of such contact...as best I can tell. As discussion on the subject suggest...this is where we have to question what is reported. How do you stand on this subject, is the 4.15dbi reported for a model over real Earth or is it Free Space results?
I've read plenty of discussions and heard even more complaining how gain is often reported or not...and these discussions always end up suggesting we need to have more not less information. This is where the almighty question of "Gain...gain over what?" usually pops up. Then we ask again with the gain just left hanging out there what are we to believe. Did you question this when Solarcon published their 9.9dbi gain? For all we know the antenna could have fell over during the test and thus we get an A99 gain in the horizontal. Maybe not a complete lie, but surely not truly accurate either. When you saw that I can imagine steaming coming out of your ears and nose, just like a lot of others.
My Eznec reports gain in DBI too and for all ground conditions, Real Earth, Free Space, and infinite ground. So IMO, the ground condition needs to be specified in order to know what that value means and for sure if you cannot really tell what the pattern for the model really is. IMO, I think the CST model does look sorta like a free space model pattern image, but there are no notation for gain and angel indicated. I see this all the time when guys publish their software results to support their words, and they often tend to leave the gain and angle details out too. Ever wonder about that. CST doesn't even show the name of the antenna in the image, nothing but the color graph that does suggest phase by the +- sign provided to be sure, but the magnitude is a very limited
indicator at best...just like it is using Eznec.
Have you noticed that the currents on the outside of the radials do not suggest a traditional looking 1/4 wave current pattern with high current magnitude at or near the base, and high voltage almost to ZERO at the top of the radials like the currents show up on the radials with Eznec?
Have you also noted that the hoop is not even indicated in the model? And if that is a voltage node (high current area) like I think you suggest...that loop would be red hot with current and surely showing up. How else will we see CMC coming from the top of the radial elements?
If the Sirio gain value is in fact over Real Earth and not over Free Space, then Eznec is not so far off showing similar gains. Do you think Siro is showing us free space gain?
imho that's not possible for a 1/2wave antenna in free space unless its packed with Dilithium crystals,
Aside from the humor, a lot has to do with whether the 4.15dbi is a gain value over Real Earth or in Free Space. It sounds like a reasonable question to ask? Are you the least bit curious about any of this?
If it is the straight skinny that Siro's gain is in FS, then there is no doubt that Eznec does exactly what Donald has suggested, and is not revealing the RF from the cone. At least it would convince me, but at this point I would have to see the model output reveal this evidence in the output images sorta' like we see from Eznec, and I would like to see the currents log.
can you add extra wires to simulate the outside of the radials to give any cm current somewhere to flow as suggested in the link?.
I don't think it is necessary to add wires to the radials already there...unless CMC can flow out of anything except an imbalance in currents at the terminating end of coaxial cable where current is maximum. If you're again suggesting that the slanted up radials on the S4/NV4 terminate in a current maximum like the termination of coax at the feed point, then there could be CMC's emanating from the tip of the radials. I just don't think that possible or is what is happening.
Donald just told me the other day when I posted asking interested members to show or describe in words where the currents look to emanate from on this S4 type of antenna. He clearly stated in his reply...that he saw CMC emanating from the feed point area at the base of the radials, and that current result was distributed along the outside of the radials and added constructively to the top 1/2 wave radiator. See below.
I think the most logical source of the currents on the outside of the cone would be CMC. Since the cone is tuned for perfect 1/4 wave resonance, it is the path from the feedpoint where the CMC is radiated.
I really don't see any point in trying to extrapolate in words what the exact magnitude of radiation would be at any given point. That is the beauty of the image from this model. It provides a visual representation of magnitude and phase as the radiation currents propagate away from the antenna and it does so in way under 1000 words.
The intriguing fact here is that the CST model revealed Cebik's analysis of a "non apparent collinear" to be 100% true years after he made the claim. No one without visual or mental impairment can look at the image and arrive at a different answer to my two questions in post #47.
