Modified Vector 4000

[Henry HPSD]

Hello guys!

Short update, still no usefull information on the other forums.

About the eznec files...well what worries me in the big difference in gain.
The first eznec file with the small diameter radiator produced over 4dBI in gain.
Now other models have shown everything form about 1..till 4dBI in gain.
The above model from "Dxer" has about 1,58dBI in "freespace" gain.
A freespace dipole would have around 1,9dBI in gain (both with alluminium loss).
Both models are more or less equal when placed 1wave length above ground.
So you see... i am worried...why would a company build such a large antenna when a dipole would profide more or less equal?

If the vector 4000 is a J-pole and the currents of the radials and the curent of the bottum half of the antenna combined is zero...then only the upper half of the antenna truly radiates...and we could see the more or less same gain.
So that would confirm most eznec models.
As what remains is a end fed dipole compared to a center fed dipole.

However....why is it then with a real thin radiator gain in the Vector 4000 can be seen as high as 4dBI that is 2dB more where did that come from?? is it a lack in the programm or is it truly possible?

About field strength..
I have been told in the past when i started measuring that measurments made within the
nearfield (within approx 1wl) are useless.
That is cause the E-field is artificial high close by compared to the H-field wich is artificial low any measurment migth be misleading.

What is off importancy is the "far field" wich starts at approximently 2wl from the antenna.
The problem is you cant give it a exact number it is different for each system.
With that field we make our "qso's". ( believe the formula was (2d)x(2d) where d is the aperture of the antenna...not sure though..(dont have any books moving at the moment)
But to be on the save side i would go along with bob and say please do more than 3wl away.

It seems to me it is not "handy" to make a microVolt measurments near the antenna.
we could also do current measurments but as long as that is say 3wl away from the antenne it doesnt tell is much cause were still in the nearfield.

Good to share thougths!

Kind regards,

Henry

 

[HomerBB]

Once again I will post something far less scholarly than you fellows who know much more than I do.

To begin with, it would be nice to actually own one of the Vector 4000 antennas in order to make comparisons.. So I must redo the homemade when I get the time to more perfectly replicate the real construction. As it is, it seemed to out perform the offset center fed sleeve dipole I had up. On the other hand, it is getting clobbered by the end fed closed sleeve vertical I put together (photo and specs on previous post). Clearly my home made mock-up of the V4k (hereafter referred to as a Q-V4k*), although at least a dozen feet higher to the feed point, and nine feet longer over all in length, has a terrible TOA. I hear things locally and in DX on the sleeve vertical that are not audible on the Q-V4k. Likewise, what I hear on both I hear more loudly with as much as 2 -3 "S" units on the sleeve over the Q-V4k. The noise floor on the sleeve antenna is lower in all circumstances making even low RX more readable. When there is no white noise in either, the end fed sleeve out performs the Q-V4k. As for TX, I get more responses to calls on the sleeve antenna than the quasi-V4k. I find myself able to make contacts with the sleeve for which I cannot adequate hold a decent conversation due to the apparent inability to RX to the extent I am TX'ing, although this could be conditions oriented. Also, a review of the SWR curve on the two antennas show the sleeve has a significantly better bandwidth. Comparisons to my 5/8^ would be, as I remember it, similar, with the 5/8^ outperforming the Q-V4k, and the sleeve antenna edging out the 5/8^ (I attribute this to losses in the coil I had on the 5/8. If I rebuild it I will outfit it with a gamma).

I might add that, although I live in the Ozarks, my elevation is around 1340' above sea level and I am near the highest point in my city. Higher elevations are too distant from me to cause serious problems with TX/RX allowing me to talk out to 30 - 40 miles at times.

So, perhaps next week, the Q-V4k goes back onto the work table (saw horses) for the more exact replication of the real V4k specs. Before I do much more, I intend to go back to a 5/8^ vertical length and attempt to tune it again to see if this Q-V4k has a better TOA at that length.

Thanks to those of you who have posted the actual dimensions on this thread.

Although I am lost to the modeling software specifics most of the time, I continue to find this an interesting read.

Charles, aka Homer

* Quasi-V4k

 

[Marconi]

Once again I will post something far less scholarly than you fellows who know much more than I do.

To begin with, it would be nice to actually own one of the Vector 4000 antennas in order to make comparisons.. So I must redo the homemade when I get the time to more perfectly replicate the real construction. As it is, it seemed to out perform the offset center fed sleeve dipole I had up. On the other hand, it is getting clobbered by the end fed closed sleeve vertical I put together (photo and specs on previous post). Clearly my home made mock-up of the V4k (hereafter referred to as a Q-V4k*), although at least a dozen feet higher to the feed point, and nine feet longer over all in length, has a terrible TOA. I hear things locally and in DX on the sleeve vertical that are not audible on the Q-V4k. Likewise, what I hear on both I hear more loudly with as much as 2 -3 "S" units on the sleeve over the Q-V4k. The noise floor on the sleeve antenna is lower in all circumstances making even low RX more readable. When there is no white noise in either, the end fed sleeve out performs the Q-V4k. As for TX, I get more responses to calls on the sleeve antenna than the quasi-V4k. I find myself able to make contacts with the sleeve for which I cannot adequate hold a decent conversation due to the apparent inability to RX to the extent I am TX'ing, although this could be conditions oriented. Also, a review of the SWR curve on the two antennas show the sleeve has a significantly better bandwidth. Comparisons to my 5/8^ would be, as I remember it, similar, with the 5/8^ outperforming the Q-V4k, and the sleeve antenna edging out the 5/8^ (I attribute this to losses in the coil I had on the 5/8. If I rebuild it I will outfit it with a gamma).

So, perhaps next week, the Q-V4k goes back onto the work table (saw horses) for the more exact replication of the real V4k specs. Before I do much more, I intend to go back to a 5/8^ vertical length and attempt to tune it again to see if this Q-V4k has a better TOA at that length.

Thanks to those of you who have posted the actual dimensions on this thread.

Although I am lost to the modeling software specifics most of the time, I continue to find this an interesting read.

Charles, aka Homer

* Quasi-V4k

Very interesting report Charles. I think it is great when guys build their own antennas from scratch, but when they tell me they work great, I do wonder how they are able to really tell. Sometimes even fried chicken, which I love, taste better one day compared to the next. You will get all kinds of arguments about testing side by side, but I bet you appreciate the finer nuances you're able to see using a switch box as in this case.

The question "Why" is open at this point, but maybe your Q-V4K is not working the collinear affect we expect is going on with the Vector. Bob is very likely right, thru his testing he noticed that by adjustments maybe he was steering the maximum angle of RF. So, maybe that is what the Avanti design is all about. Maybe your Q-V4K is not doing that presently even though it seems to work just fine otherwise.

Were you surprised at the difference you see by comparison? I'll bet it was not so obvious when you first put the Q-V4K on the air, right? This is exactly why I prefer to compare antennas side by side.

I saw your new creation the other day, but have been wrapped up in the Vector discussion, and presently I'm recapping the whole mess for good information. So, I just didn't have time to ask. However, with your report today, I'm really interested in the details of how that thing is constructed and fed, if you could share.

Good luck and keep us posted.

 

[Henry HPSD]

Hi Guys,

Another thought about where radiations along a antenna is the biggest...

Now, again i am not a antenne guy who knows all.....as many of us..learning is what its all about..Dont read this as "my truth" just thougths, combined we'll get there.

SW. suggest: where he measures the strongest fieldstrength there Could be the biggest radiation.
Well...im not too sure about that. First off all where do you measure?
you cant measure near the antenna as the field where we make use of "the farfield" has not been esthablished.
So any measurment close to the antenna does not tell us much.
Another thing is..what are we measuring? is it ony the Volts? or the current or both?
a elecotromagnetic field is made up out of more than Volts alone so if we are measuring the volts alone...it is of no use. For current the same ofcourse.

We know we have the farfield wich is basicly a electro-magneticfield so buildt up out of current and volts.
We know this is esthablished at least 2wl perhaps more (depending on antenna) away from the antenna.
Soi find it hard to pronounce there where the current is low, radiation is max as it is made up out of both.

Besides that, i never heard of a antenna which took advantage of its radiation along its ax.
(ofcourse not accounting top-hat or other "matching" technics as the J-pole)

Just a thought...

Kind regards,

Henry

 

[Marconi]

I am trying to recap what good information we can take away from Bob’s great thread on the Vector/Sigma4.

Bob, in post #1, 10/09, you showed us a picture of Shockwave’s modified Vector with shorter radials set at a wider angle, and told us SW had NOT yet tuned it for distance. A month later in post #10, you told us you had the measurements and that SW’s modified Vector had been tuned for best results. A couple of days later in post #15, Shockwave gave us the dimensions and says the antenna was tuned for 11 meters, and that the BW and gain looked better without elaborating---better than what? He can actually measure BW, but only by on-air testing can he get any idea of gain or else depend on modeling or an antenna range. He did comment it was for sure better than a 5/8 wave however, and again no details as to what the comparison was, the BW, the gain, or both?

SW, as best I recall you were not modeling this antenna at that time, only physically testing for distance, right? So, can you give us more information on the issues above?

 

[Marconi]

Here is a thought based on Bob's EzBob currents: easybob currents pictures by ukmudduck - Photobucket

Can we all agree that we never see such images as we're talking about and that show up on Bob's charts---indicating voltage?

These modeling programs always make such output available for a reason---to suggest how the antenna is radiating.

IMO these currents that we see indicated as magnitude of the current over the length of the element, as noted in Bob's charts, are representative of the potential RF emitted. This also suggest the potential and magnitude of RF power at a point on the element that may be generated, regardless of the Far Field or Near Field issues being raised here, that do not apply to the issue of where the RF emanates from.

In this case, it is not an issue of whether we can measure this stuff or not or how far away or how close we are. The question was---where does the RF emanate from on the element?

Of course if you want to discuss Far Field and Near Field that is fine, but that is other concern, like Bob's testing at a distance---another issue.

 

[Henry HPSD]

Here is a thought based on Bob's EzBob currents: easybob currents pictures by ukmudduck - Photobucket

Can we all agree that we never see such images as we're talking about and that show up on Bob's charts---indicating voltage?

These modeling programs always make such output available for a reason---to suggest how the antenna is radiating.

IMO these currents that we see indicated as magnitude of the current over the length of the element, as noted in Bob's charts, are representative of the potential RF emitted. This also suggest the potential and magnitude of RF power at a point on the element that may be generated, regardless of the Far Field or Near Field issues being raised here, that do not apply to the issue of where the RF emanates from.

In this case, it is not an issue of whether we can measure this stuff or not or how far away or how close we are. The question was---where does the RF emanate from on the element?

Of course if you want to discuss Far Field and Near Field that is fine, but that is other concern, like Bob's testing at a distance---another issue.

Appriciated the input! but am afraid my english lacks.
Are you asking in your first part about:
1-have we all never seen this before?
2-Do you want to know if it is current or voltage wich you are seeing?
(ps it is current that you see.)
It is only to show what the current does. This is intresting to reduce the corona effect with high powers or to know where you can "attach" something to your antenna.
To show what the radiation does for your antenna you need to have the far field pattern.
Both the elevation and azimuth or of intrest.

The second part..you lost me..ill try tomorrow with a translater (bed time here!)..sorry again.

The third part...
If you want to know where does something radiate..you need to know how to measure it.

The fourth part...
I am not intrested in a discussion about far or near field either...
But, one needs to know what one does.
The near field is not so "intresting" for antenna use..
The far field is what we use to make a qso..
I am looking at it as a car.. i do not want to know how much heat is produced in the engine..i wanne know what distance i can drive and at what speed.

Ps..attached you can find a JPEG of the E field of the near Field pattern.

Good thread!!

Kind regards

Henry

PS SW! just saw your remark about the length and the source! true well done )!! off to bed now.

 

[Marconi]

Appriciated the input! but am afraid my english lacks.

Are you asking in your first part about:
1-have we all never seen this before?

No, I'm asking if you have ever produced a voltage distribution report using your Eznec? Or stated another way: Henry do you have an option in Eznec to produce a distribution of voltage report like you do with the current distribution?

My question was rhetorical and that may not be fair considering your native language, sorry.

2-Do you want to know if it is current or voltage wich you are seeing? (ps it is current that you see.)

No! and I agree.

It is only to show what the current does.

The current distribution detail certainly does show what the current does, as you note. It also indicates how much and where on the element the current is graphically and in addition it shows the magnitude in amps statistical in the report. Does Eznec do the same for voltage?

This is interesting to reduce the corona effect with high powers or to know where you can "attach" something to your antenna.

Maybe, but you'll have to explain how this applies to the question.

To show what the radiation does for your antenna you need to have the far field pattern.

But this was not the question Henry. SW and I disagree where the RF emanates from on the element, at the voltage node or the current node, nothing more.

Both the elevation and azimuth or of intrest.

Maybe, but you'll have to explain how this applies to the question.

The second part..you lost me..ill try tomorrow with a translater (bed time here!)..sorry again.

I have an idea what you mean when you refer to "the second part," but rather than speculate and be wrong, I’ll wait for another time.

The third part...if you want to know where does something radiate..you need to know how to measure it.

That is true if you are talking about where the RF radiates too and how far, but again that is not the question. The question is, where does the current emanate from, the current node or the voltage node.

The fourth part...
I am not intrested in a discussion about far or near field either...
But, one needs to know what one does.
The near field is not so "intresting" for antenna use..
The far field is what we use to make a qso..
I am looking at it as a car.. i do not want to know how much heat is produced in the engine..i wanne know what distance i can drive and at what speed.

Agreed, and some consideration for near and far fields is important, but again that is not the question.

Ps..attached you can find a JPEG of the E field of the near Field pattern.

You will have to describe how this image relates to the question.

Thanks for the questions,

Eddie

 

[HomerBB]

Good luck and keep us posted.

Ok. I put the info on another thread so I wouldn't get this one off topic.

 

[Marconi]

Ok. I put the info on another thread so I wouldn't get this one off topic.

That is great. Something new and fresh. This thread is interesting but getting out of hand, and I had as much to do with that as anyone I suppose. I'm just lucky the pay is so good.

 

[Shockwave]

Marconi,

I've noticed that modifications to the antenna do not seem to effect the radiation angle at all in EZNEC. The only thing that seems to change the radiation angle is the height above ground and that makes a big difference as with most antennas. The modifications have more effect on gain then take off angle.

Again, I believe my large loop Vector has too large a loop. I have seen gain increases over the stock Vector design when the loop diameter is increased however, my measurements past the ideal point. At the time I did not investigate in any depth the effects of increasing radial length as Bob has. From modeling the antenna it seems more gain can be had through radial length rather then loop length.

My modified Vector had increased bandwidth from the stock version. The antenna was tuned for gain on 11 meters but I noticed the improvement in gain on 10. On 11 meters the gain didn't change much at all. In reflection I feel the better gain on 10 was due to a better VSWR match and less to do with true gain.

In comparison to my old S-827, the Vector always has more bandwidth and the stock one has more gain. My radials were too short to add gain on 11. When I peaked the gain out on the FM antenna the loop was 30.5 inches long. That's just over 1/4 wave at 98 MHz. The Vector loop is under a 1/4 wave.

Soon I'm going to use my adjustable FM prototype to investigate the real world effects of increasing the radial length beyond 1/4 wave. Radial length and loop diameter will be varied while I watch for gain in the receive mode with a field strength receiver modified with a digital meter for the highest sensitivity.

This is so much easier to do on FM when the entire antenna is less then 9 feet and a full wave above ground is only 10 feet. EZNEC has a wonderful feature of being able to convert the dimensions from 98 MHz back to 27 MHz once I see what works best in the field. This time longer then 1/4 wave radials will be tried without as much expansion of the distance between them and the radiator as the Avanti patent suggested.

 

[Henry HPSD]

Hi All !

I have posted a new thread "electro magnetic field nearfiel far field" in order to try anwering the above questions related to that subject.
The reason is simply to keep this good thread for what is what intended the "modified Vector 4000".

Kind reagards.
Henry.

 

[Marconi]

Hello All,

Good to see the discussion continues !
The 1st model was made in a couple minutes as the sizes of the antenne were not known yet.
At this moment i have a model with the "true" lengths.
I still have problems with getting honest results as the program (no mather what segmentation length etc) keeps giving me "error". Or resson to believe it could be off.

The Problem with eznec is more or less a issue with any programme. It has limitations.
As one pumps up now.

Now, I have taken the liberty to ask Kirk Mcdonald at Princeton to look into it,
Told him about the discussion going on at this froum. He at his turn came up with mr Alan Boswell who is very familiar with Nec engineering.

My knoweldge of the programm is limited. I know how to use it not how it works.
Those guys know how it works. So if anyone can come up with a solution they can.

... my hopes up for them in getting "true" readings.

Just bougth a new house and very busy with that, havnt read all the other post yet..
But surely will do when time permits.

Kind regards,

Henry

Henry don't rush cause I know you're busy with the new house and everything else in life, but just curious to follow-up if you've heard anything positive from Alan Boswell about the NEC programing problems with the Vector?

 

[Marconi]

Marconi,

I've noticed that modifications to the antenna do not seem to effect the radiation angle at all in EZNEC. The only thing that seems to change the radiation angle is the height above ground and that makes a big difference as with most antennas. The modifications have more effect on gain then take off angle.

SW, you may be right if you've done some additional modeling that actually made comparisons. IMO, all of the models presented to us so far---none were intended to be comparative to another. Henry tells us his original model used incorrect dimensions out of convenience and not withstanding even that the wire diameters used were all incorrect, very small, and not tapered tubing. Those elements were likely no where close to stock electrically and I don't see how it is possible for the algorithms used to calculate this important mix of factors and do so dependably. I may be wrong, but I think you suggested that you fixed Henry's length dimensions, except for the diameters and sent those results on to Bob.

Later Dxer makes a model using the best dimensions he had of an original Sigma4 with three radials. According to Bob there is a noticeable difference between the original S4 compared to the Vector 4000 with 4 legs. With all of these differences among the various models so far, producing very similar results, are we to believe that Eznec just ignores all of the tedious parameters entered or what? I don't think we've seen a model of the Vector yet that has the correct input using tapered tubing. Dxer got close using the original Sigma4, and he posted two different length radiators showing very little difference in gain or angle. His longest model was 319.2", but I don't know the points where these measurements were taken from. My S4 shows to be 331" from the bottom of the hub to the tip, so I can't account for mine being a foot longer that Dxer's 319.2". He shows a small space at the bottom that may be his source, but that area looks like the space for the mounting bracket and is not included in my overall length, so I'm longer still.

SW have you run models with the parameters (radiator/radials) longer to see if the angle was affected like Bob suggest in his assumption that he may have steered the maximum angle of radiation lower? If not, what information do you see in the models presented so far, that suggest to you that Bob is wrong about his steering idea?

Again, I believe my large loop Vector has too large a loop. I have seen gain increases over the stock Vector design when the loop diameter is increased however, my measurements past the ideal point. At the time I did not investigate in any depth the effects of increasing radial length as Bob has. From modeling the antenna it seems more gain can be had through radial length rather then loop length.

You say here that you did not investigate the effects of increasing radial length like Bob suggested, but you claim much further back in time that adding length to the radials on you FM antenna does exactly that. You also claim here that you have seen improved gain with wider angles and that a larger hoop showed improvements since 11/2009 with your Modified Vector for 11 meters. Do you believe that modeling trumps your real world experiences you saw back then when you claimed improved results and thus you changed your mind? If you went past the best point in increasing the angle do you have any thoughts on why your field testing failed you? Do you still think that Avanti missed the boat on the wider angle idea or did you just miss something?

My modified Vector had increased bandwidth from the stock version. The antenna was tuned for gain on 11 meters but I noticed the improvement in gain on 10. On 11 meters the gain didn't change much at all. In reflection I feel the better gain on 10 was due to a better VSWR match and less to do with true gain.

Bob talked about seeing improved BW when tuning for best signal at a distance. Did it seem strange that you made the antenna longer than stock and yet the best match still appeared to be in 10 meters instead of 11? I read what you claim below, but you still claimed improvement over the stock Vector. What happened to the tuning thing that is supposed to fix resonance when you set the gamma for the best SWR. I hear your words, but I don't get it? Why didn't you just readjust the gamma match to bring the antenna down in frequency like Bob and you both claim happens with just a change in the gamma settings?

In comparison to my old S-827, the Vector always has more bandwidth and the stock one has more gain. My radials were too short to add gain on 11. When I peaked the gain out on the FM antenna the loop was 30.5 inches long. That's just over 1/4 wave at 98 MHz. The Vector loop is under a 1/4 wave.

Now this claim may make some sense, that the shorter 81.5" radials were too short for the antenna in 11 meters, but again why didn't that show up in the field testing for the prior 6 months if you can see that now?

SW, don't take all my questions personally. Last summer when I did some comparison work on my antennas, I made plenty of really stupid mistakes, just ask Bob who I pestered with much of my results. I proved one thing to myself---doing things on the fly don't generate real dependable results. It is not that you were doing things necessarily on the fly, it is that I'm trying my best to rehash what I read and to try and make some sense of it all.

To this point, I'm ruling out the results for the modeling thus far. I hate to ask you folks that have already done modeling to try and establish a Vector model that follows the specks as close as possible to be used as a base line for further comparison, but if we can gain anything from modeling then IMO that is necessary even to start.

I think Dxer has already modeled or was planning to model the New Vector 4000 using true diameters for the tubing and taper. I think he's already done the original Sigma4, but his length does not agree with the length I show. Maybe the difference is how he measures his overall length for the 25.277' foot or the 26.6' foot models he posted. I don't know which is supposed to be the stock S4 however. If his modeling efforts here were to compare different lengths for the radiator, then the foot long difference in overall length made very little change in gain and no difference in the angle shown.

IMO, with a good model for the New Vector 4000 as a base line antenna, then maybe it would be simple to modify and compare while making the Vector with a longer radiator, shorter/longer radials, at the same angle of 10 degrees or with different angles.

Maybe we still might not understand how it really works, but with a big "MAYBE" we might be better able to visualize what works and what doesn't work best within the range of 27.7' - 31.5" feet with some changes in radial lengths as well. The doubt I have right now is that no matter what measurement differences we might use---we may not see the differences we would expect.

I would also be curious to see at what point the in-phase affect comes and goes and what a convential 3/4 wave ground plane with 4 horizontal radials looks like modifying this base line model.

Soon I'm going to use my adjustable FM prototype to investigate the real world effects of increasing the radial length beyond 1/4 wave. Radial length and loop diameter will be varied while I watch for gain in the receive mode with a field strength receiver modified with a digital meter for the highest sensitivity.

Have you been able to do this yet?

This is so much easier to do on FM when the entire antenna is less then 9 feet and a full wave above ground is only 10 feet. EZNEC has a wonderful feature of being able to convert the dimensions from 98 MHz back to 27 MHz once I see what works best in the field. This time longer then 1/4 wave radials will be tried without as much expansion of the distance between them and the radiator as the Avanti patent suggested.

Good luck,

 

[Marconi]

Hope this info may help with the discussion on the Vector. I should have taken the info from the Sigma4 file since it uses know dimensions but I used the 26.6' Vector. The 1st pic is with currents on. The 2nd is current and phase. Also attached is the output file showing more info.

Post edit. Just added the file with the wire #'s turned back on for the text file.
1-9 is the main Vert
10-13 are the radials
14 and up the hoop.

Dxer posted the following images from his model of a Vector from some source. As he notes, the first image is with currents on and the second is with currents and phase on.

Currents on:


Currents and phase on:


Dxer, my Sigma4 with three radials is 331" long from bottom of hub to tip. All of the Vectors I've seen are longer. What was the 26.6' or 319" Vector you used here, or better still what points did you use to measure?

In Henry's original modeling image that Bob posted, and here with Dxer's first image shown above, I have been assuming all along that the antennas were in phase, just like Bob suggested with Henry's model. I was assuming this was due to the images where both 1/2 wave and 1/4 wave currents were showing up on the same side of the radiator. Am I corn'fused or what?

Now with that said, in Dxer's second image above, which is noted to show current with phase on, it looks to me that the red line currents of the two current areas of the Vector are actually out of phase---just like we might expect to see with a regular J-pole---and maybe with a typical 3/4 wave GP.

How say you?