Question on the Vector

[Marconi]

Bob, I asked earlier if it was ok to do a 3/4 wave monopole model without the radial hoop on top. The purpose was to show that I see similar results indicated in the Skeleton Sleeve Antenna article as I do with Eznec. When the radials are slanted up from the horizontal and set close to the monopole we see the resistive part of the match go up and the reactive part changes noticeably. So, the complex impedance drops a little and the frequency goes higher, unless we fix the reactance and return the antenna to resonance.

When I add capacitance to the radiator by making it longer the reactance is brought back near to zero, then the resistive part of the match drops, and this is what I think that Cox is describing.

The net result between a 3/4 wave antenna with horizontal radials, and one with slanted up radials when adjusted back to resonance...is the match does not change much due to raising of the radials, but the blocking by cancellation in the cone area greatly improves the pattern, gain, and angle for such a 1/4 multiple long radiator that here-to-fore didn't work too good for low angle radio transmissions.

To me, what goes on down in the cone area is simply good old cancellation theory, that allows a 3/4 wavelength radiator to work well at low angles. And to say it another way, this design pushes the 1/2 wavelength radiator with the maximum current maximum up higher by 9 or more feet above any other GP mounted on a similar mount, and IMO that is enough for Avanti to claim it is of an advantage, to say nothing about it saving much lateral space around the antenna mount, and working well near other objects and near the Earth.

Be sure and check out the last sheet for the match (source data) in each model to follow what happens with this antenna. IMO, this is all about the matching, and the cancellation of the bad currents we see from the base of the monopole that disrupts the low angle radiation possible...giving us the benefits we see with this remarkable this antenna.

I have done a model of the Skeleton sleeve antenna also. Check the old thread again and open the links in the first post not the one I posted using Ansoft, and I think you will see just about the same results as those attached below.

Bob, I think I posted enough results so that you might be able to compare it to the Skeleton Sleeve article...if they provided any performance results too.

 

[Shockwave]

BTW, the 3/4 wave wave monopole I modeled with slanted up radials like the NV4K, but without the hoop attached, shows what I am suggesting here. You and Donald cannot show any evidence that the currents on the outside of the Vector cone are CMC. The pattern looks wrong for a 1/4 wave radiating element too.

I say it again, due to transmission line currents inside the cone...we have cancellation and thus little to no RF into the far field. Thus the cone helps block most of the detrimental out of phase current in the cone area and does not ill-effect the tune of the antenna much and the bad effects that cause a 3/4 wave radiator to make a high maximum angle of radiation.

Donald might could prove this one way or another if he could produce some real details for the CST currents data. I don't know anybody else that has a connection with Sirio in such matters like he does.

I mean no offense but everything you said is complete hogwash once again and NONE of it can be replicated in the field. How does this end fed antenna differ from all the rest and have no CMC current like you suggest??? Since that's not possible tell us why you think the CMC would be drawn to another point rather than the resonant 1/4 wave cone?
Since you're now willing to admit the cone feeds the 1/2 wave radiator above it, it should be just as obvious to you this end fed 1/2 wave must produce CMC at its feedpoint which is the top of the cone. It must flow back down the outside of the cone because there is no other path. I'll remind you once again when the cone is not properly tuned CMC is noticeable on the coax. Hint!

Do me another favor and stop telling me I can't show proof the base of the Sigma radiates significantly. The reality is you don't have the ability to replicate the test required to prove yourself wrong or you're not willing to try going beyond words like those of us who have taken the time to obtain the hard evidence themselves.

Donald has already proven every thought you have about the Sigma wrong. Proof takes work Marconi, that's why you don't have it in this case. Since success in my job required it, I did the leg work necessary to identify the phase and magnitude of the cones radiation. The only details you need to know about the currents in CST are displayed in the 1/2 wave shape of a 1/4 wave current in the cone.

The one detail behind everything about the 90 degree phase shift taking place in this non apparent collinear. To remain in denial and keep the debate going you MUST ignore this fact and dismiss it as an anomaly or error in this program. Besides, according to what we've seen in the past from you, you'll just say CST is wrong or claim another anomaly.

You're too hung up on getting your hard evidence so don't pretend some current log from Sirio is going to stifle your misinformation now. The only way to get the hard evidence that your theory cannot be replicated in the field is to do the collinear field tests. That would without question prove everything I've claimed but you'll never do this or get someone you consider unbiased to do it for you prior to sharing the inaccurate humble opinions you do. With that in mind, don't ask me for more proof until you're willing to use the undisputable test I've already provided you with in great detail.

 

[Shockwave]

To me, what goes on down in the cone area is simply good old cancellation theory, that allows a 3/4 wavelength radiator to work well at low angles. And to say it another way, this design pushes the 1/2 wavelength radiator with the maximum current maximum up higher by 9 or more feet above any other GP mounted on a similar mount, and IMO that is enough for Avanti to claim it is of an advantage, to say nothing about it saving much lateral space around the antenna mount, and working well near other objects and near the Earth.

Remember you're basing this entirely off a model that doesn't even predict the phase of the antenna correctly. Expecting accurate results under these conditions is ridiculous. You're also contradicting the free space CST model where height makes no difference and the fact a 1/4 wavelength makes no difference at the frequencies and heights I work with but yet we still get at least 2dbd when side mounted in the same location as the dipole was. Please reserve opinion for when you can support it or when it doesn't contradict what can be proven in the field if you took the time.

 

[Marconi]

Donald, the only details you have ever posted on anything you've talked about regarding this subject...is the animated pattern from Sirio's CST's model of their New Vector 4000, and it is not enough. Some body even cropped out the pertinent performance facts from the image you posted.

Donald, this is what a real image of the CST antenna pattern provides the user. See the data block on the left side of the pattern is missing. We see the A/m graph on the right side...I wonder why the other block of data was left out of this particular image and who did it?

 

[Marconi]

Looks like the same thing is going on with your end of this new forum as I've been seeing Donald. I was posting at the same time and it looks like you had something unexpected happen...so you didn't get to leave a message, right?

 

[Shockwave]

To me, what goes on down in the cone area is simply good old cancellation theory, that allows a 3/4 wavelength radiator to work well at low angles. And to say it another way, this design pushes the 1/2 wavelength radiator with the maximum current maximum up higher by 9 or more feet above any other GP mounted on a similar mount, and IMO that is enough for Avanti to claim it is of an advantage, to say nothing about it saving much lateral space around the antenna mount, and working well near other objects and near the Earth.

Remember you're basing this entirely off a model that doesn't even predict the phase of the antenna correctly. Expecting accurate results under these conditions is ridiculous. You're also contradicting the free space CST model where height makes no difference and the fact a 1/4 wavelength makes no difference at the frequencies and heights I work with but yet we still get at least 2dbd when side mounted in the same location as the dipole was. Please reserve opinion for when you can support it or when it doesn't contradict what can be proven in the field if you took the time.

 

[Shockwave]

The forum has become extremely difficult for me to use since the new change. The page takes forever to load too. Very resource intensive. My response to your post refuses to publish with your quote so here it is for the third try. The edit my post option does not work either so we will see more mistakes.

To Marconi: Remember you're basing this entirely off a model that doesn't even predict the phase of the antenna correctly. Expecting accurate results under these conditions is ridiculous. You're also contradicting the free space CST model where height makes no difference and the fact a 1/4 wavelength makes no difference at the frequencies and heights I work with but yet we still get at least 2dbd when side mounted in the same location as the dipole was. Please reserve opinion for when you can support it or when it doesn't contradict what has already been proven in the field.

I've also posted much more than the CST file. I provided a specific field test to you that forces you to identify the phase of all radiated current correctly before you can stack another 1/2 wave on top. There is no "wiggle room" in this type of phase test but you still claim I have no proof simply because you cannot use the proof I offered.

I've already explained why Sirio removed their brand specific information in the model they provided me. You're insulting and misleading to imply the image provided was anything less than a "real CST file" I guess we can't expect more from someone who can't test their own theories.

 

[Marconi]

Your edit feature will return as soon as you close the site and return.

 

[Marconi]

QUOTE="Shockwave, post: 497850, member: 10882"]To Marconi: Remember you're basing this entirely off a model that doesn't even predict the phase of the antenna correctly. Expecting accurate results under these conditions is ridiculous. You're also contradicting the free space CST model where height makes no difference and the fact a 1/4 wavelength makes no difference at the frequencies and heights I work with but yet we still get at least 2dbd when side mounted in the same location as the dipole was. Please reserve opinion for when you can support it or when it doesn't contradict what has already been proven in the field.[/QUOTE]

Donald you are right, but I have attempted to explain what I think about this anomaly with Eznec and the why and what Roy may have done in designing this software.

IMO, the crux of this issue has to do with the way that NEC2 handles the connections for the wires, and what Roy did about that to make modeling easier to use. But no body has listened to what I suggest in this regard...so it is worth repeating.

In many cases I can make a model show the corrects current phasing, and I've shown you how that works with a simple dipole, but you have to be disregarding the warnings about currents that Roy told us about in his manual.

I have found that if I make a S4 with just 3 radials I can fix the models currents to look right in my minds eye.

If I do the Vector with 4 radials, however, I can only fix two wire ends that connect as NEC2 demands, so the current work right. This leaves two important long radial wire connected wire 1 end 2 to wire 2 end 2 and NEC2 does not like that. You just ignore the warning from Roy that I posted a while back to Bob.

I'm thinking that Mr. Cebik possibly never messed with this particular CB antenna before, but when Bob described the S4 and its construction...maybe Cebik realized that Eznec would have difficulty in addressing the taper, and the angles created by two tangent wires that are close together. This is just a guess on my part, but IMO this antenna model can be done using Eznec, and I'm convinced I've done it.

I've tried talking to Henry and DB to see if they could help me prove this possible with Eznec currents. I even used a simple horizontal dipole to show you how this works...but no body is buying the idea. Maybe this is also why Roy felt a stronger need to make Eznec user friendly, rather than worry about what it did with proper wire end connections and the tabular currents log. I can't even find anything that Cebik wrote on the subject of how Eznec handles currents.

I think I even posted this simple dipole idea sometime back right here on WWDX, but nobody was even interested.

If you had paid attention to the examples of the dipole I sent you before, I think you would have seen whether the currents were properly indicated or not...the performance factors for the antenna would be the same...either way.

 

[Shockwave]

I see the cost and enormous amount of time I've wasted modeling this design in EZNEC as a complete waste I wish I'd never done in the first place. The reason is it mislead me to using the wrong phase for some time before I realized the program is off by 90 degrees.

I promise to not even consider another EZNEC model until the point which the model works with a 90 degree phase shift between 1/2 wave collinear sections as it does in the field. I've heard you say before you think you have an accurate model based on the manner your wires are connected now.

All I asked was for you to check and see if the model can now represent what works in the field with a 90 degree phasing delay between collinear sections. All you need to do was add the 4 wires and determine if the phase delay was 1/4 wavelength or 1/2 wavelength in electrical length.

You cannot claim to have fixed the phase problem in the model until the model replicates the 90 degree phase shift that works in collinear field tests. I don't care how many wires you use to form the cone, you're claim is false until it works with a 90 degree delay.

I feel like I keep saying that over and over in an attempt to drill it in your head that what you have DOES NOT WORK WHEN PUT TO THE TEST IN THE FIELD. Who gives a damn if a faulty model says your idea is right until you can demonstrate this in the field like I have?

100 years from now there still will not be a single person in the world to make a collinear Sigma work with the 180 degree phase delay EZNEC indicates will work perfectly, suggesting the original antenna is only a 1/2 wave. Any day you want to invest the time you can prove it only works with 90 degrees, showing the original antenna has a phase correction taking place to make the entire antenna radiate constructively.

I recognize it's not easy for you to conduct these fields tests accurately due to health reasons otherwise I think you would have shut your mouth and gotten off your ass to do them some time ago. Let me ask you this question. If the field test does show what I say with a 90 degree phase delay, do you understand how this proves the Sigma is much more than an elevated 1/2 wave??? I need to know this otherwise we have much more ground to cover first. Please answer this last question if anything because it is the crux of this issue entirely.

 

[bob85]

Bob, I asked earlier if it was ok to do a 3/4 wave monopole model without the radial hoop on top. The purpose was to show that I see similar results indicated in the Skeleton Sleeve Antenna article as I do with Eznec When the radials are slanted up from the horizontal and set close to the monopole we see the resistive part of the match go up and the reactive part changes noticeably. So, the complex impedance drops a little and the frequency goes higher, unless we fix the reactance and return the antenna to resonance.

When I add capacitance to the radiator by making it longer the reactance is brought back near to zero, then the resistive part of the match drops, and this is what I think that Cox is describing.

your model seems to fit the article with regards the frequency at which the antenna is purely resistive going up, resistance going up a little and impedance going down as you move the radials closer to the monopole eddie,
it is also noted you need to adjust the antenna lengths to bring it back to resonance,

can you explian what cox means here

"The operation of the open sleeve can be divided into two modes, an antenna mode and a transmission line mode. This is shown in Fig 8

"the total current flowing into the base of the open-sleeve antenna may
be broken down into two components, that contributed by the antenna mode, IA, and that contributed by the transmission line mode, IT."

 

[Marconi]

I recognize it's not easy for you to conduct these fields tests accurately due to health reasons otherwise I think you would have shut your mouth and gotten off your ass to do them some time ago. Let me ask you this question. If the field test does show what I say with a 90 degree phase delay, do you understand how this proves the Sigma is much more than an elevated 1/2 wave??? I need to know this otherwise we have much more ground to cover first. Please answer this last question if anything because it is the crux of this issue entirely.

Donald it is a fair question. Give me a bit of time. I'm modeling a 1/2 wave collinear (super J) J-Pole using the calculator at this location: http://users.marktwain.net/aschmitz/antennas/jpolecalc.html

I think this model uses a 1/4 wave phasing stub to drive the added top 1/2 wave. I will see if Eznec handles this as noted in the article and report. However, be aware that I see the same bottom condition I see in the S4, a little incomplete cancellation that does radiate a bit unless the setup is the worst case scenario.

 

[Shockwave]

The total length of the folded conductor used in the phasing stub you show in this example is 38 inches. That is almost the exact length of the 1/2 wave radiator above it. This phasing section may be a physical 1/4 wavelength however the electrical path is 1/2 wavelength and creates a 180 degree phase shift between its input and output.

It is exactly what is required to stack one 1/2 wave over another 1/2 wave. It is 100% too long to stack a 1/2 wave over a 3/4 wave that already has 90 degrees of phase correction taking place. This phasing section will work on the Sigma in the EZNEC model because the program fails to see the cones significant in phase radiation just like you.

Now if only you could go the next step and check out what happens in the field. I'm trying to determine when the day comes that someone else confirms only a 90 degree phasing section will work on a collinear version, if you will understand how this proved the original antenna is a 3/4 wave constructively phased radiator?

Be aware you see the cancellation you see because EZNEC always fails to show the PAIR of currents on the cone that have a 90 degree offset in phase between them but yet combine on the same radiator to form the pattern that has you EZNEC baffled.

If it were just a matter of reversing the direction of the wires in the model to get the right phase, why didn't Roy suggest this would correct the phase discrepancy and why has no one been able to show an EZNEC model that shows what we see in the field after the fact?

 

[Marconi]

can you explian what cox means here

"The operation of the open sleeve can be divided into two modes, an antenna mode and a transmission line mode. This is shown in Fig 8

"the total current flowing into the base of the open-sleeve antenna may
be broken down into two components, that contributed by the antenna mode, IA, and that contributed by the transmission line mode, IT."

Bob, my ARRL reference does not have a Fig 8 for the OS antenna section. Could these items be noted as "Equivalent circuit of an open sleeve antenna," and/or is it the section on "Current Distribution?"

You might have to tell me what all this means, because I'm terrible on understanding circuits.

 

[Marconi]

If it were just a matter of reversing the direction of the wires in the model to get the right phase, why didn't Roy suggest this would correct the phase discrepancy and why has no one been able to show an EZNEC model that shows what we see in the field after the fact?

Donald, I have never had anyone confirm this idea, but I see it fix the current reported back with the simple center fed two wire dipole I sent you long ago, trying to explain what I saw.

Can you deny one of these two models below corrected the problem and the other didn't?

1. one made wrong with two wires, wire 1 end 1 connected to wire 2 end 1, which will show the error in the currents...equal magnitude with opposite phase is the result to correct the problem with the currents.

2. another made correct with two wires, wire 1 end 1 connected to wire 2 end 2, which will make the currents show correctly...equal magnitude with equal phase like a real dipole current distribution should show.

Donald, the models below reflect what the standard dipole should show in free space. The match is correct, the gain is correct, the angle is correct, and the SWR is correct on both models. All performance factors are correct, but the currents are different, and all I did was change the way I entered the wire descriptions in the software.

Bob, I posted this warning Roy gives his users about how this program works to fix NEC2 issues with currents a while back. Does this make sense now?