sigma4 article is online

[Henry HPSD]

Owh almost forgot...

Here is online about how to construct a well made J pole..

http://cb-antennas.com/?page_id=399

please notice the difference is setting with matching to SWR versus frequency.

Now, in donald his Dominator version the "feedpoint" has a fixed location
(at the bottom) logical he will need to change the gamma match settings.
If he changes length....logical he will see reactance etc.
Changing lenght is changing frequency isnt it..

Kind regards,

H>

 

[bob85]

Eddie
This should help clear up what i mean by bad masts lengths,
http://www.hamradio.me/antennas/j-pole-antenna-should-i-ground-it.html

 

[HomerBB]

Thanks everyone for your answers. Admittedly, some of the questions I have answers to already, but I wanted plain spoken replies that more folks who have followed the S4/V4k discussion less time than others of us.
I notice slight differences of perspective still between Henry's and Bob's answers, and I see similarities.

By "professional use" I was primarily referring to Donald ' use of 5his antenna type.
As for ham's not using 5/8 wave antennas too much and CB ops using them a lot I think can be equally traced to reasons other than the "CB Mythology" around them. I personally think it likely has more to do with CBERS working a single band and Ham's needing antennas that are fit for multi band use. It seems to me that Ham's quickly turn to them in mobile applications where they are talking over fewer bands because of the mounting options being more limited. If only a truly 5/8 wave mobile CB antenna were possible for 27 MHz!
That is a tangent that the article isn't exploring and we are referring to only a as point of reference so I'll not say more.
As to why more manufacturers do dipoles? One of the answers is on Ebay. So they can charge $30 for less than $10 worth of wire and insulators.

So, the answers I understand, yet, they are not fully addressing one unresolved conundrum - why has this antenna outperformed other monopole antennas in vertical orientation, dipole or otherwise, at the same tip height. Instead of saying it hasn't been demonstrated to be so when beside a few enthusiasts like me Donald has the confidence of 1.4k commercial users of this antenna who have experienced otherwise. This is the point being dismissed out of hand or explained away with arguments only.
Understanding what the COST plot actually demonstrates is a step in the direction of sorting through the data we have in hand toward knowledge. Whether that plot was forwarded as a model of significant proof of the workings of this antenna, but was not perfectly understood does not answer the question of the antennas better performance when used in place of other monopoles.
I know (although I'm not a professional) it out performed anything else I put in the air with current maximums at the same elevation.

I know I seem to be arguing. I apologize. Nor do I wish to be perceived as obstinate. I'll leave that title to another. I just think that saying what something is not isn't the same as saying what it is.

Marconi has said he's seen little to no difference between antenna types for quite a while. If anyone wanted to look back over my reports of antenna types I've built and reported on you could see I've rated them all based on more factors than percormance, ease of construction, weight, beauty, etc, but only the V4k has commanded the top spot when narrowed down to performance only. I was berated for testing my Astroplane at the same tip height against other antennas and would not reverse myself on it be a use I knew it was designed to be flown that way and reported no other antenna worked better than it did except the V4k.

So, there is more to the story, IMHO.

Homer.

 

[The DB]

I've played around with the model some more...

While, as I found earlier, I am unable to change the angle of radiation when there is an earth present. As I am unable to modify this I took a different tack of exploration. I compared two identical models, one in freespace, and one over an earth. What I found is that I get maximum gain when the freespace version of the model has the same angle of radiation as the model over earth.

For example, if an antenna height over an earth nets a given angle of radiation, say 8 degrees, if I modify the model so in freespace the model to also give me an 8 degree radiation angle, and use that over the earth, I get the peak gain.

Taking this one step further, there is a second peak to be found. If my angle of radiation is at 8 degrees, and I modify the model to show -8 degrees in freespace, when adding in an earth there is another peak in gain at that 8 degree angle of radiation. This second peak is not as strong as the first peak I mentioned, but it is there.

I think this discovery will actually change an aspect of how I see antennas and gain. The goal, when designing an antenna to use, should not be to seek the peak horizontal gain in freespace, but instead a freespace angle that will match the angle of radiation of the antenna over an earth. If it is an antenna design where you can steer the angle of radiation in freespace, such as the GHZ24 model Henry provided.

I also see this as evidence of Bob's and Donald's claims of being able to manipulate the antenna for better far field gain. I don't see it as necessarily changing the angle of radiation of the far field gain, but simply steering the antenna's radiation to match the angle of radiation the height/environment dictates the radiation angle will be. In essence, the antenna is being tuned to the environment...

Now that I think about it, there are a few models I played in the past that could also demonstrate this effect. I will have to play with this some more...

Something else I think this demonstrates is that NEC2 does not show how the far field gain comes to be, only that it is there. It doesn't show that x amount is from direct wave while y amount is from reflection off of an earth, ect. It simply says that this is what the pattern looks like in the far field. That being said, I think this shows that steering the antenna's angle of radiation does effect the gain of the far field over an earth, even if it doesn't change the angle of radiation of that antenna. One of my models based on this idea shows nearly 1 dB in gain over a dipole at the same tip height... Although admittedly part of that additional gain comes from the antenna being more efficient than the dipole reference according to 4NEC2, and the fact that we would loose a small amount (I'm guessing about .2 dB give or take) of gain after adding a matching device to that antenna.


The DB

 

[Henry HPSD]

Hello Homer,

Arguments are not a problem, but i like to keep things real.
Saying there are 1400 uses who have experienced otherwise....that makes me wonder ?

As mentioned before, the power the Dominator can handle...is max 3Kw.
It is my guess we can count say 90 + percent as relative small radio stations.
(there are probably a couple who use them as "mobile use" as CBC)
Though overall..say 90 percent plus.. (Donald give us a hint pse)
Take a look at your own local radio station...
You might know who runs it....tell me what expectations do you have of the guy who is using the antenna ?
So..Im afraid im not counting them all in a way that they have "experienced otherwise" but..sure i can imagine them all being happy !
But wouldnt you agree that also goes for al the fanatic Imax and A99 users.
Heck, i have got people using my moxon claiming it has better ears cause its a closed loop hihi...

lets do it otherwise...give me proof of 1 percent of those 1400 or 1500 happy clients who can provide gain measurements as they should be.
And as asked ? wouldnt the FCC have measured at least some of them ?
And wouldnt the ERP of them be to large if the gain was real ?
Or am I missing something ? US FCC broadcast rules is not my cup of tea.

Oke about the HAMs, ...but what about the all the others ?
all "pro" users ...what about "pro" antenna companies ?
Why don't you see them there ?
Why don't you see the dominator antenna in space / aircraft / military / all broadcast ....besides one company..... (owh yes, and quite some pirates sell them)

Situations why the antenna could outperform are described.
Though I am afraid i can not express each situation, and your question asked to explain them is logical, however it will end in an endless debate.
One will have to find out why the difference exist at your own location.
Is it mast length ? Is it CMC ? is it reflections ? Is it tip height ? etc.
You could probably write a A4 paper full with possible options.

I can only tell what will happen in "best" or "expected" circumstances
And in that case, i believe it is most likely the antenna will outperform others..
Just like you have experienced.

So please don't get me wrong, I do not consider the antenna as "bad".
In fact I consider it to be among the best.
But sadly not because of Donald his explanation nor claims.

Actually I think the antenna handles "things/issues" better as many other antennas. (think i also mentioned that not sure thought)

I did my up most to keep the article as simple as possible, if it still is beyond the reach of some..oke so be it...its not meant to be a tutorial with a zero starting point.
(although i really tried hihi)

But i am more than happy to explain things...
(where i can...i don't know all for sure)
Perhaps there are more topics that could be of interest to some ?

 

[Marconi]

I've played around with the model some more...
While, as I found earlier, I am unable to change the angle of radiation when there is an earth present. As I am unable to modify this I took a different tack of exploration. I compared two identical models, one in freespace, and one over an earth. What I found is that I get maximum gain when the freespace version of the model has the same angle of radiation as the model over earth.
For example, if an antenna height over an earth nets a given angle of radiation, say 8 degrees, if I modify the model so in freespace the model to also give me an 8 degree radiation angle, and use that over the earth, I get the peak gain.

DB, how do you modify a model in free space to produce a different radiation angle?

 

[HomerBB]

@DB
I'd like to see this demonstrated by models of other types of antennas, too... interesting.
@Henry HPSD good reply, and not different in some respects than I have given to others about antenna performance.
I appreciate your work on this.
I see what you're saying about the employees of the radio stations, but I am unwilling to lump Donald into a bunch like bananas.

Perhaps this is an improvement upon a basic design, the J-Pole in this case, as virtually all antenna types are improvements upon the dipole. I remain interested in exactly what that i.provement is and just how it is acheived. (Thanks to DB looking for more clues).

There are cases where supposed improvements have not proven to be so for me, like the Extended Zepp Dipole I put up being less receptive and motlre noisy than a basic dipole at my house. I just figured it must be mounted in the wrong place . . .

 

[The DB]

Eddie, one way is to change the z variable in the model which changes the overall length of the vertical in inches, shortening this length will lower the freespace angle of the model.

You can also change the rh variable, which sets the ring height. Making this height higher will also lower the freespace radiation angle.

If you don't know where these variables are, open the provided .nec file in a text editor like notepad, look for the lines that start with SY.


The DB

 

[Henry HPSD]

Guys...wouldnt that be logical ? reflected wave in phase ?
The "snooker" effect remember ?
But you do not want more gain in a take off anlge...

What you guys forget each time....this is not helping for those CB users who use the antenna to talk with locals...

It does not help to increase the signal strength at distant horizon.

 

[The DB]

@DB
I'd like to see this demonstrated by models of other types of antennas, too... interesting.

That is something I intend to do at some point hopefully in the near future...


The DB

 

[Henry HPSD]

@HomerBB :
I see what you're saying about the employees of the radio stations, but I am unwilling to lump Donald into a bunch like bananas.

That makes two of us !
It was because of my faith in Donald that i did this.
I still have faith in him, and I believe him...i believe he did his up most.
But i cant support his theory, and am disappointed he keeps on going.
I was hoping he went after "the search" why ...instead of holding on to his currents in cone collinear theory thing.

Anyway...
The effort done by all is appreciated !
But one should be carefull.
Just like now..some seem "surprised" that gain rises..
I know most of you guys are thinking "owh more gain in my main lob.."
Must be better...

But im afraid it is not.
Well it is if you want more signal at 10 degrees take off angle for example.
But that "gain" will only help "there"

It will decrease you signal strength at distant horizon.
It might be that some of you have those what confused ?

Kind regards,

H>

 

[Marconi]

I don't think that I've ever said that the S4 model is not a good antenna. Even though I have heard X number of negative reports from guys regarding the Vector not being up to par.

I spent a whole month several year ago, changing, comparing, and testing my S4 all by itself on the same system.

At that time Bob was talking to me via emails about reactive feed line transformation. I'm going to go back and see if I can find this testing in my antenna notes, and I will report what I was thinking at the time, only if it seems it could be informative. It might take me some time however, I have 4 large composition notebooks full of notes that are not indexed.

The point is however, that I saw several different effects going on with the antenna during that process least of which was my S4 acting with bad TVI like a J-Pole. To support this idea that I was seeing good results even though Bob and I were both disappointed in the fact I never say any results like Bob was telling me I could.

To reinforce my ideas about my S4 being a very good antenna, in spit of the fact that I was not successful in making it perform like Bob was suggesting, I recalled when I earlier first got the antenna up and working, I was receiving requests from several locals to see if I could get them one of these antennas. They would not have done that unless they saw something they liked on their end with contacts from me using it. The rest of the story, which I have recounted, is not important, but the details are posted here on WWDX.

I was getting good local reports at the time, and for me is what was important to notice in these words.

For me, this discussion has always been about how the S4 design works, not about how it performs compared to another antenna.

Sometimes however, we do talk about some performance and comparisons trying to justify our claims on both sides...but again this is not about performance. I see the difficulty in our lack of meeting of minds as always being a conflation of these two separate ideas at some point.

The links I posted earlier clearly describes the J-Pole, and that is just being disregarded as to why it is suggested that the S4, has some aspects of the J-Pole. That does not mean to me that the S4 is a J-Pole for all the reasons already described.

Now we have the performance and the J-Pole out of the way...what is left? IMO, Henry has pretty much focused on that aspect. Either you believe that the 1/4 wave cone is providing RF into the Far Field area that can benefit communications or your don't.

IMO, it is fine for us to believe either way, but the discussion next should be can we prove either to be correct.

In my own experience with my SD'r or my Marconi x design, which both have a 1/4 wave radiator, I see the gain and angle advantages that longer antennas offer uses... disappear as I get the maximum current areas of the antennas near or equal in height.

Homer disagrees with that idea except in the case of his using he AstroPlane antenna. I think both of use were just making judgments in the case where we made up our minds on this...so that question has not been resolved.

The idea whether the bottom cone of the S4 radiates or not is the question we need to focus on IMO. To do this we need some convincing presentation for how and what is going on in the cone area of the Sigma 4/New Vector 4K antennas, not Donald's Dominator.

I have tried to both explain and show using Eznec how I see the currents working in the cone area. We have heard Donald and Bob give their ideas, and now we read and see Henry's report...do we need more investigation, another opinion with a presentation, or have we got all we really need if we give this idea due consideration that is not over our heads in scientific details.

What has been most convincing to many has been the animated model that Donald posted, but there is no data support for the interpretations that have been made, and can be made. Actual support of these seeming convincing ideas is still missing, and I don't think any progress beyond just words is ever going to change anybody's mind if this is all there is.

I discount Donald's idea, because my Eznec models show similar content in the Antenna View of the antenna with currents turned on, but my interpretation based on the current data details, which are complicated and different, renders my ideas not convincing either.

Henry can you or your CST friends possibly clear this up any...outside of teaching us all to understand antenna current theory?

 

[Henry HPSD]

What question eddie ?
Sorry not irritating meant...but not sure what u r asking...
And allready in bed from cellphone isnt helping either..

Good nigth all...

 

[The DB]

Anyway...
The effort done by all is appreciated !
But one should be carefull.
Just like now..some seem "surprised" that gain rises..
I know most of you guys are thinking "owh more gain in my main lob.."
Must be better...

But im afraid it is not.
Well it is if you want more signal at 10 degrees take off angle for example.
But that "gain" will only help "there"

It will decrease you signal strength at distant horizon.
It might be that some of you have those what confused ?

Kind regards,

H>

That is tested easily enough. I went through the entire range of changes in one of the models where I was watching the low angle lobe gain and watched the 0 degree angle gain. When a ground is present, this gain figure did not change, at all. The changes I am making are affecting the strength of the lobe, yes, but they are not affecting anything at horizontal as that gain stays exactly the same according to NEC2.

So I have to ask, how is it making it worse if it is at an angle that, is completely unaffected by said changes? Unless you are saying NEC2 is wrong in this case?


The DB

 

[bob85]

Eddie,
What is it about Henry's article that makes you think it does not address the question of what the CST animation is displaying?,

To my eyes the animation displays the near magnetic H-field in
A/ m and direction around the conductors,

If it was the usual method of measuring field strength from antennas it would display the electric E-field in V/m,
the stuff that makes your heathkit needle move,

I can't think of a better way to explain its the near magnetic H-field than Henry's FEKO images show us,
For sure it would be easier to visualise if FEKO used the same colors as CST but included the arrows for direction as well,

If anybody has an alternative explanation that can be proven by links to respected sources id like to see them, Im always looking to learn,

Homer
i have argued for years the astroplane should be tested as the patent intended it to be used at the same tip height,

your other antennas?

did they all have an efficient low loss matching system ?

all made out of the same tube with the same resistive losses ?

were they all decoupled from any conductive mast & the coax choked & have radials for return currents?

did you test them with an un-modulated carrier in stable conditions with people out in the distance and without other antennas close bye?

i have seen good and bad results from end fed antennas such as a99 and imax, they are not as bad as some people make out,
no worse than other cheap endfed halfwaves such as a silver rod copy,
i can't think of a well constructed end-fed halfwave on the market to compare to other antennas,

When you don't decouple them and give the return currents a path that won't potentially spoil the pattern you are playing a game of luck with mast and feed-line currents as W8JI tells us,

lots of people run ground wires to their mast/antenna without any thought about common mode,
very few people think about the electrical length of their mast and its common mode impedance even though they may have used a choke at the feed-point,
They may DC isolate the antenna from the mast by wrapping the mast in insulating tape or similar, its still capacitively coupled,

how many people believe a j-pole connected to a conductive mast is a good idea?
lots of ham projects suggest they should be, a few articles even suggest its needs to be for the antenna to perform correctly,

These things can lead people to the conclusion that some antennas are junk, don't perform well, cause tvi, lip burning rfi, speech processors not working, distorted audio, noisy rx, touch lamps turning off and on, the list goes on,
Its why some people say they work ok and some people hate them with a passion,

Its not so much the antenna as how its installed,

My fork handle choke and radial solution is capable of turning what seems like junk into something perfectly useable even if it made some people laugh .