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sigma4 article is online
- Thread starter bob85
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Homer, you're a good man and I'm in total agreement with everything you said above. Unfortunately Henry's actions are revealing his motives and intentions negatively and he is no longer responsive to reasoning.
While I've enjoyed the time I've spent sharing in this forum and think it's one of the best out here, I have weighed the benefits against the damage these types of unfounded personal attacks can have on my work and will no longer be participating in the forum discussions as a result. As you can see by all the carelessly liable threats being made, any attempt to correct these mistakes seems futile.
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Take care, Donald.
Maybe you can find a way through all this to change your mind.
My email is available should you ever want to communicate.
Maybe you can find a way through all this to change your mind.
My email is available should you ever want to communicate.
If you see it that way...your vision Donald....but I understand.
Although it is not needed, I will remove that name on the site Donald
As i really have no interest in making you look bad.
For those interested....lets talk about antennas again !
Including you Donald...if you want...
as long as it is without the personal things and about facts
...Im happy...! Perhaps i can explain or learn.
Kind regards,
H.
Although it is not needed, I will remove that name on the site Donald
As i really have no interest in making you look bad.
For those interested....lets talk about antennas again !
Including you Donald...if you want...
as long as it is without the personal things and about facts
...Im happy...! Perhaps i can explain or learn.
Kind regards,
H.
Henry, you've given me the option to participate and agree with you in complete disregard of decades of opposing field results with the threat of defaming me at anytime if I show how they or anyone's results contradict your theory. Thanks but no thanks for your offer which feels more like blackmail. You're actions in this very area will reflect what your true intentions have been without further input.
Homer,
I don't claim there is no radiation from the cone,
Henry's article shows what radiation we can expect due to the radials not been parallel,
There will also be some small radiation due to imbalance which Henry mentioned, I don't know how much but not enough to make 2-3dbd raw gain or it would show up in cst and other software,
Look at what sirio did with the updated vector,
They extended the cone to 1/4wave and shortened the monopole to 3/4wave claiming a lower radiation angle, I don't dispute that either,
You could likely fine tune that a bit in your own mounting situation,
Antenna gain IS measured "across the street" as Donald aptly put it, In the far field but not miles away where other factors come into play,
You need to eliminate those other factors as best you can to get the raw gain of the antenna, relative field strength vs other antennas at the fringes of coverage is not the gain figure,
I don't have an issue with claiming that in a typical installation the significantly taller antenna could provide 2-3db over another antenna out on the fringe of coverage, especially if its mounted on top of the tower in the clear rather than side mounted,
Claiming 5.15 dbi is misleading as that implies significantly more raw gain,
If that was true the gain would show up in the far field "across the street", claiming otherwise defies the laws of physics, Im not asking you to take my word for it,
Look at how real antenna measurements are taken by professionals in anechoic chambers and antenna test ranges,
They don't wander around with an old field strength meter 50 miles from the transmitter comparing one antenna on top of the tower vs a dipole side mounted lower down,
Henry tested a real vector with decent HP test gear, And built the test collinear that proved a 2 x 1/2wave with 180 degree stub does work as eznec tells us,
He also had the vector modeled with cst and modeled it in other software,
They all show similar results so the claim that cst is the only software that can model the antenna is not true,
It uses MOM like other software and the guys at cst said that's the way to model it,
The magnetic near H-field plot sure does look pretty but its not showing what we thought it was.
I don't claim there is no radiation from the cone,
Henry's article shows what radiation we can expect due to the radials not been parallel,
There will also be some small radiation due to imbalance which Henry mentioned, I don't know how much but not enough to make 2-3dbd raw gain or it would show up in cst and other software,
Look at what sirio did with the updated vector,
They extended the cone to 1/4wave and shortened the monopole to 3/4wave claiming a lower radiation angle, I don't dispute that either,
You could likely fine tune that a bit in your own mounting situation,
Antenna gain IS measured "across the street" as Donald aptly put it, In the far field but not miles away where other factors come into play,
You need to eliminate those other factors as best you can to get the raw gain of the antenna, relative field strength vs other antennas at the fringes of coverage is not the gain figure,
I don't have an issue with claiming that in a typical installation the significantly taller antenna could provide 2-3db over another antenna out on the fringe of coverage, especially if its mounted on top of the tower in the clear rather than side mounted,
Claiming 5.15 dbi is misleading as that implies significantly more raw gain,
If that was true the gain would show up in the far field "across the street", claiming otherwise defies the laws of physics, Im not asking you to take my word for it,
Look at how real antenna measurements are taken by professionals in anechoic chambers and antenna test ranges,
They don't wander around with an old field strength meter 50 miles from the transmitter comparing one antenna on top of the tower vs a dipole side mounted lower down,
Henry tested a real vector with decent HP test gear, And built the test collinear that proved a 2 x 1/2wave with 180 degree stub does work as eznec tells us,
He also had the vector modeled with cst and modeled it in other software,
They all show similar results so the claim that cst is the only software that can model the antenna is not true,
It uses MOM like other software and the guys at cst said that's the way to model it,
The magnetic near H-field plot sure does look pretty but its not showing what we thought it was.
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I think right here is the point of departure between my interest in the antenna and part of the debate this thread has experienced. I am not interested in the actual gain figures (5.1, 2.2, 10.5 is not my focus). I know that is a necessary part of an antenna discussion. I am interested in is what causes this antenna to function so well in the long distance.
"I don't have an issue with claiming that in a typical installation the significantly taller antenna could provide 2-3db over another antenna out on the fringe of coverage, especially if its mounted on top of the tower in the clear rather than side mounted" as well, however, I have experienced my performance edge with the NV4k antenna when it was installed with the current maximums of shorter antennas at the same elevation.
My point has been lost in the stream of debate. I realize how gain is measured by professionals and why it is done that way. I have not been concerned with that, except that the discussion has only centered around gain so measured vs speculated gain many miles away while omitting why this antenna works better many miles away. The net result of this omission in the discussion is to leave one with the impression that neither I, nor you, nor anyone else who has so claimed to have seen improvements with this design when the current maximums were equal heights with other antennas truly ever saw this phenomenon (either we are deluded, or lying for some unfathomable reason).
That portion of the discussion has been one of those pieces that has a history in the pathway of seeking answers. I don't model, so I could only speak to this as you did at times - because the answer was not forthcoming from models with Eznec software the difference in what we all seemed to be seeing in the CST animation was believed to be an indication of Eznec's failure. I have no problem with things better learned along the way. That's why I joined the discussion 2 or 3 years ago. I'm not sure anyone has really belabored that point in this thread except that singular points of discussion have been lumped into whole packages because of the heated discussion, and there has been a tendency to "throw out the baby with the bath water"
Frankly, I am glad to know the antenna can be modeled successfully by a seasoned modeler. This allows more folks to provide insights.
Exactly, at least for an opportunity to turn our attention to other possible answers (other than it is an accident) to why it does so well.
At this point, I remain unrelentingly attached to my position of this antenna outperforming others consistently, and it isn't due to its length presenting a higher current maximum.
Both you, and Henry, and I think Marconi, agrees this is a 1/2 wave antenna sitting atop a highly efficient matching network (similar to a J-pole).
I must be a little thick headed on this point, but a half wave antenna will only perform as a half wave antenna, as I understand it. So when current maximums are presented in the same place a Nv4k should not do any better than the CFHW dipole, yet it does. I am missing something in this discussion that answers that one.
i get the out of phase current in the lower 1/4 wave of the antennas physical length is contained. I do not get the idea that all the current is canceled so there is no contributing in phase current on the cone. The self canceling phases are within the cone. The cone is physically attached to the the antenna in a direct ground setup on the feed point hub. I understand no reason the outside of the cone will not resonate with current.
We have discussed feedline currents, and antenna currents, and compared the cone to a sleeved coaxial antenna where useful CMC presents on the outside of the coax braid/cone. Now the answer you previously provided, or perhaps it was Henry, is that full cancellation on the inside of the cone prevents any current from being on the outside of the cone (or very little due to an imperfect cone shape), yet I see no explanation of why the outer surface of the cone does not once again cause the antenna to send it radiation skyward.
1.) why is there no current on the outside of the cone from the bottom of the cone as it is grounded to the rest of the antenna there, and
2.) why it is not once again a 3/4 electrical antenna given the currents inside the cone have canceled each other leaving us with a nice clean metallic conducting cone surface to put current on?
Why the questions make sense to me is that we have three (3) surfaces in the bottom 1/4 wave, not two - the center radiator, the inside of the cone, and the outside of the cone.
Another reason why this remains a matter of interest to me is that it seems to me that the idea of a circulating current around the individual radials of the cone do not present a commonly phased current in direct opposition to the phase of the current on the center conductor. What am I missing?
If the cone radials have individual currents then once again, what prevents them from making this an electrical 3/4 wave antenna? After all, there would be currents on the outside of the cone due to the circulating radials currents. Or. because the current is canceled in the cone then there is no circular current possible.
It seems contradictory to claim no (or too little) current on the outside of the cone due to inside the cone cancellation, but allow circular currents around each cone radial of the same cone. Personally, I think the explanations are too weak so far and appear more mud on the windshield.
These questions are not for me alone, but for others who I think could use explanations.
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Homer mentions gain figures, and I have a question on them. What do the gain figures tell us about what the signal strength is where the receiving antenna is? We look at patterns that, for many receiving antennas, will be far overhead, especially when we are talking about reception at a distance.
Say your antenna is one wavelength high and under the given conditions has a radiation angle of 10 degrees, and the receiving antenna 30 or 40 miles away is also one wavelength high. By the time your signal gets to that antenna, the area of maximum gain that we seem to love to focus on will be far higher than the antenna itself, and that is before factoring in things like the curvature of the earth, which will only make the problem worse.
Why not look at surface wave data instead? For example, here we have a modified Vector model (Homer's dimensions plus a modification or two), a 5/8 groundplane, and a 1/2 center fed dipole all at the same tip height as measured at 100 Kilometers out (that is 62 miles). The 5/8 wavelength and Vector models have a matching device added to help compensate for the matching networks that are built into their designs.
On the left side we have the height in meters from ground level. Across the bottom we have the strength of the signal in micro-volts per meter (uV/m). So the further to the right at a given height, the stronger the signal is at that point.
We can look at what is happening at any given distance out, and for a given range of heights above the earth. Doesn't this better represent the tests that Donald, Bob, Homer, and others have reported?
So I have to ask again, why are we depending on a raw gain figure that in no way represents the testing that was done and reported on this antenna to form an opinion?
The DB
Say your antenna is one wavelength high and under the given conditions has a radiation angle of 10 degrees, and the receiving antenna 30 or 40 miles away is also one wavelength high. By the time your signal gets to that antenna, the area of maximum gain that we seem to love to focus on will be far higher than the antenna itself, and that is before factoring in things like the curvature of the earth, which will only make the problem worse.
Why not look at surface wave data instead? For example, here we have a modified Vector model (Homer's dimensions plus a modification or two), a 5/8 groundplane, and a 1/2 center fed dipole all at the same tip height as measured at 100 Kilometers out (that is 62 miles). The 5/8 wavelength and Vector models have a matching device added to help compensate for the matching networks that are built into their designs.
On the left side we have the height in meters from ground level. Across the bottom we have the strength of the signal in micro-volts per meter (uV/m). So the further to the right at a given height, the stronger the signal is at that point.
We can look at what is happening at any given distance out, and for a given range of heights above the earth. Doesn't this better represent the tests that Donald, Bob, Homer, and others have reported?
So I have to ask again, why are we depending on a raw gain figure that in no way represents the testing that was done and reported on this antenna to form an opinion?
The DB
1.) why is there no current on the outside of the cone from the bottom of the cone as it is grounded to the rest of the antenna there, and
2.) why it is not once again a 3/4 electrical antenna given the currents inside the cone have canceled each other leaving us with a nice clean metallic conducting cone surface to put current on?
Why the questions make sense to me is that we have three (3) surfaces in the bottom 1/4 wave, not two - the center radiator, the inside of the cone, and the outside of the cone.
Another reason why this remains a matter of interest to me is that it seems to me that the idea of a circulating current around the individual radials of the cone do not present a commonly phased current in direct opposition to the phase of the current on the center conductor. What am I missing?
Hello Homer,
Antenna radiating current is different from the "current throug a conductor"
You have to think them "seperatly" though there are similarities.
1- There isnt a 'real" outside of the cone...
It has 4 radials and "current" will be equal in them.
Ehm, the current on the outside of the "radial" will be equal to that on the inside of of the same radial.
You could have currents on the "outside", which can be different compared to the "inside".
But then we will need to create a situation where a 11 meter singal "cant" go though".
The cone needs to be really "dense" like a coax cable or so...
(faraday effect)
Now, since the "room" between the radials is too far to large....there will not be an "outside" and "inside".
Now, im not sure if I fully understood your you question ?
As you speak specificly of the base ?
2 Because its a RF cycle....the wave is "27 Mhz" its a repeating "thing".
There is a "ongoing" progress...
The wave goes up during its "period"..and again...and again etc.
There wont be a period that there is "nothing".
3 The current in the radials are in direct opposite phase compared to the main radiator.
Think of a groundplane antenna.
You can imagine the "hotside" to the vertical radiator...
And the "cold" side to the radials.
Now, we can feed that groundplane with a gamma-match...if needed...DC grounded etc.
We are going to turn the radials upwards....
The "current" wont change, we still have the "cold" side on the radials (say the "-" )
And the "plus" on the centre radiator...and there for "opposite".
hope it is of use...
Kind regards,
H>
2.) why it is not once again a 3/4 electrical antenna given the currents inside the cone have canceled each other leaving us with a nice clean metallic conducting cone surface to put current on?
Why the questions make sense to me is that we have three (3) surfaces in the bottom 1/4 wave, not two - the center radiator, the inside of the cone, and the outside of the cone.
Another reason why this remains a matter of interest to me is that it seems to me that the idea of a circulating current around the individual radials of the cone do not present a commonly phased current in direct opposition to the phase of the current on the center conductor. What am I missing?
Hello Homer,
Antenna radiating current is different from the "current throug a conductor"
You have to think them "seperatly" though there are similarities.
1- There isnt a 'real" outside of the cone...
It has 4 radials and "current" will be equal in them.
Ehm, the current on the outside of the "radial" will be equal to that on the inside of of the same radial.
You could have currents on the "outside", which can be different compared to the "inside".
But then we will need to create a situation where a 11 meter singal "cant" go though".
The cone needs to be really "dense" like a coax cable or so...
(faraday effect)
Now, since the "room" between the radials is too far to large....there will not be an "outside" and "inside".
Now, im not sure if I fully understood your you question ?
As you speak specificly of the base ?
2 Because its a RF cycle....the wave is "27 Mhz" its a repeating "thing".
There is a "ongoing" progress...
The wave goes up during its "period"..and again...and again etc.
There wont be a period that there is "nothing".
3 The current in the radials are in direct opposite phase compared to the main radiator.
Think of a groundplane antenna.
You can imagine the "hotside" to the vertical radiator...
And the "cold" side to the radials.
Now, we can feed that groundplane with a gamma-match...if needed...DC grounded etc.
We are going to turn the radials upwards....
The "current" wont change, we still have the "cold" side on the radials (say the "-" )
And the "plus" on the centre radiator...and there for "opposite".
hope it is of use...
Kind regards,
H>
which / who's raw gain figure (@ dB )?
And yes, it does look better...doesnt it
Kind regards,
H>
And yes, it does look better...doesnt it
Kind regards,
H>
DB, I'm curious to know how adding a match to a model effects results when modeling.
This report looks to be producing some very detailed performance information about the models.
Do you know or can you check if the models did not include the match, would they still show similar or the same results?
Could we tell the difference in signal or be able to hear and copy the Vector, and not the 5/8 or 1/2 wave for example?
This report looks to be producing some very detailed performance information about the models.
Do you know or can you check if the models did not include the match, would they still show similar or the same results?
Could we tell the difference in signal or be able to hear and copy the Vector, and not the 5/8 or 1/2 wave for example?
which / who's raw gain figure (@ dB )?
And yes, it does look better...doesnt it
Kind regards,
H>
I'm talking in general. I don't recall seeing any data from modeling, specifically NEC2 modeling, in direct regard to this before the image I posted above... To my memory, every plot where a gain figure is being shown or compared is using far field gain data that, in most cases, is far above the receiving antenna for what would be a local contact, especially at a distance.
Mind you up until recently I did the same thing...
Maybe those of us trying to model this antenna need to take another look at what we are modeling, and what claims we are making from said modeling... It is our job to make sure the information we are giving fits the situation at hand, is it not?
I'm not saying that the claims being made are necessarily wrong, but are they really in the same context as the claims from real world measurements? Look at Donald's claims based on the numbers he is measuring. His antenna is at broadcast heights, and the receiving antennas that are measuring said received signal for said comparison are much lower in height, namely the height of a standard FM radio in, say, a car. Can anyone honestly relate a signal with a greater than zero angle of radiation to the signal that Donald and others are measuring with his equipment?
Or Homer, who has used this antenna design to talk to people no other antenna he has put up would allow him to talk to? In his case, it isn't a very high antenna transmitting to a very low antenna situation such as in Donald's case, it is a situation of an antenna that is mounted one wavelength high making ground wave contacts. The people he talks to would have antennas that are far below the gain figures we seem to constantly talk about. He is looking for the reason why this antenna works as it does.
If we, as modelers, are saying people's real world data is wrong based on our models, but we aren't properly duplicating the situations the real world data has collected, are we, as a group, perhaps part of the problem?
The DB
There was no match on the center fed 1/2 wavelength antenna, however, it was tuned via overall length to have almost no reactance, getting as close to how I would tune such an antenna in the real world.
For the 5/8 wavelength groundplane antenna, which also has four 1/4 wavelength horizontal radials, I used a low pass L network for the matching as it was more efficient than the high pass L network. The Vector used a high pass L network instead, as for that antenna design it is more efficient.
When it comes to matching networks, I specifically stay away from matching networks where one could manipulate the network's losses, such as the pi network and the T network. I don't want potential changes in said networks to manipulate output data. The L networks simple give an optimal situation.
Also with matching networks, the closer an antenna is to a X=0 R=50 match the less losses affect the antenna with such a network. So the harder the matching network has to work to get the feedpoint to that point the more losses you will have.
In the end such additions to my models don't perfectly duplicate the effects of real world matching networks, but they do get me that much closer to real world results as any antenna that requires matching will have some additional losses from said matching that otherwise won't be calculated. The fact that there are effects to an antenna requiring such a device, I feel my results would be tainted if I don't including such a device in my models when comparing to other designs that would require differing amount of matching to match to a feedline.
In the case above, the Vector, which had a much better natural tune, was affected far less than the 5/8 wavelength antenna, who's natural feedpoint impedance was the worst of the three.
If you want to see the difference, this is the same three models under the same conditions, only no matching networks added...
The DB
@ dB...
I all ready provided such a plot in the article ....showing indeed that 2 dB distant"gain" difference..Using enzec pro/4 (see article)
Where all others were "optimal"
We had in the beginning in this thread some talk about it ?
I provided to you:
The indication of the surface wave on 4nec2 with "pre-caution".
With the "pre-caution" as i wasnt sure if it was "wise" to do so, as i was worried about possible errors within 4nec2.
If I may ask...have you done some verifications ?
Did you came across some "issues" ?were they inline with the results I provided ?
In aspect tot hte negative lob...
Yes you can measure a negative elevation lob.
With that said, he (donald) did his testing at relative low height.
The reason why the surface wave etc its not applied as a" general rule"
is various;
1- different groundconductivity will have influence
2- different polarisation will have influence
3- the "type" of modeling will have influence
4- things like the "transmitter" height above ground....will have influence etc.
5- are all "other waves" included as well ?
6-what distance ?
7-what freq
etc etc etc..
So in order to make it a "general" thing we all....need to "agree" on several aspects.
That wont happen hihi.
Where if we would just publish the gain in "freespace" we wouldnt have to worry about it..and all is "fair" but there are "situations" where that figure isnt giving a good indication.
Though similair "data" is often used for MW broadcasting stations
Often inserted in geographical maps.(sure a couple will be online somewhere)
Yes, I do model (depending on job) on maximum strengt at horizon
Or maximum at TAO. Perhaps now my words make sound logical ?
I also havnt used it that long...it was with the J pole i first used it.
"became appearant" as normally im into horizontal beams and not the "strongest distant vertical signal hihi".
Good to see you get the hang of it...important to realise
Kind regards,
H>
I all ready provided such a plot in the article ....showing indeed that 2 dB distant"gain" difference..Using enzec pro/4 (see article)
Where all others were "optimal"
We had in the beginning in this thread some talk about it ?
I provided to you:
The indication of the surface wave on 4nec2 with "pre-caution".
With the "pre-caution" as i wasnt sure if it was "wise" to do so, as i was worried about possible errors within 4nec2.
If I may ask...have you done some verifications ?
Did you came across some "issues" ?were they inline with the results I provided ?
In aspect tot hte negative lob...
Yes you can measure a negative elevation lob.
With that said, he (donald) did his testing at relative low height.
The reason why the surface wave etc its not applied as a" general rule"
is various;
1- different groundconductivity will have influence
2- different polarisation will have influence
3- the "type" of modeling will have influence
4- things like the "transmitter" height above ground....will have influence etc.
5- are all "other waves" included as well ?
6-what distance ?
7-what freq
etc etc etc..
So in order to make it a "general" thing we all....need to "agree" on several aspects.
That wont happen hihi.
Where if we would just publish the gain in "freespace" we wouldnt have to worry about it..and all is "fair" but there are "situations" where that figure isnt giving a good indication.
Though similair "data" is often used for MW broadcasting stations
Often inserted in geographical maps.(sure a couple will be online somewhere)
Yes, I do model (depending on job) on maximum strengt at horizon
Or maximum at TAO. Perhaps now my words make sound logical ?
I also havnt used it that long...it was with the J pole i first used it.
"became appearant" as normally im into horizontal beams and not the "strongest distant vertical signal hihi".
Good to see you get the hang of it...important to realise
Kind regards,
H>
- No one is chatting at the moment.