sigma4 article is online

[bob85]

Something something else to think about Donald,

You told us you tested your vhf antennas on a 10ft pole, that's not far off 1 wavelength above ground,

look at Henry's chart of received signal strength at 30km for the vector vs dipole at 1 wavelength above ground,

Its 2db over a dipole, yes 2dbd right inline with your claims, i did not doubt you had measured close to that figure vs a dipole,

But that's not 2dbd freespace requiring collinear gain,
Its what the vector is capable of compared to a dipole with their feedpoints about 1 wavelength above ground.

 

[Marconi]

Hey Bob check out the difference my Eznec models show below where it is predicted for the Sigma4 vs. the NV4K to specs...as little differences when compared. This suggest there is little difference between 3 radials vs 4 radial applications also.

Donald is correct, the Vector shows the top of the cone is more well placed near the phase shift zone for the radiator. But, also take note of the currents on the mast for the Vector. It looks like the advantage for the improved balance created by the longer cone...forces the upper portion of the mast to now show out of phase with the top 1/2 wave radiator...when the model is made over real Earth. Maybe isolation will fix that and improve the gain.

I have to also admit, that the Vector's FS pattern looks much better than the Sigma4.

Next I will post these models with an isolation fix, and see if it will improve the gains for the models over real Earth. You will have to imagine that a choke or some other device will have to be used to fully stop the CMC on the feed line, and this antenna looks to need some decoupling help.

 

[Marconi]

Here are the model results Bob after I effectively isolated the mast by 5" inches.

This is pretty simple stuff and maybe not so difficult to follow showing the effects that Eznec predicts regarding the issues with CMC on the mast, and shows in spite of the fact the Vector shows the better balance results that Donald suggest...the Vector is likely a bad actor when it comes to CMC's on the mast and feed line.

I think if the models are anywhere near accurate for real world installations...then it may help explain why manufactures don't bother with solving CMC issues for their customers, and how guys like you that think about details in antenna installations...can give us good advice that can help us improve our station a bit.

Again, when the antenna gurus give us the "wow is me" sad stories about the bad issues with very small effects of CMC on the mast or feed line...the real issues may be more "bark than bit."

Just and opinion that I know happens in the real world all the time, without much grief.

Models below with two overlays to show the gain for both antennas.

 

[Shockwave]

Bob, I find it somewhat funny that it was you that convinced me to come into the forum 6 years ago to defend against the "J-Pole camp". That you were sure the base of the Sigma had to be radiating in order to see the effects and gains you've noticed over other antennas. Now after just a month of listening to Henry, the base don't radiate and you only get gain when you have the famous lucky length of mast.

After you've described exactly how you and Henry see the fields fit his theory, I find it ironic that this same image fits the solid cone theory too. Even though you say it doesn't, I have no problem viewing a solid cone as showing the same image we see in CST without it having to be 4 fields rotating around individual radials.

It seems suspicious to me that Henry's gain measurement should hold any more weight than mine or someone like Robert from KOLG. I also don't buy for a moment that all 2db gain is from mast or coax radiation. Doesn't that also mean a worst case length of mast could also take away an equal amount of gain??? Having a 2db variable is hard enough to believe but from what I'm seeing this theory allows for a variable of plus and minus 2dbd. That's ridiculous.

Over the years I've been tuning these antennas, I've moved 3 times. Each location used a different tuning location and mast length. One hardly used any mast on top of a flat roof and I've never been able to replicate these wild swings in gains that are now being claimed.

How come no one has given DB the time of day when he's confirmed the ability to productively steer the pattern on the distant horizon in his models? Are his findings less important than what Henry has published? I unfortunately see DB as one of the only ones left here giving what could be considered a totally unbiased opinion while still willing to consider all reasonable options. Especially ones that fit the time tested results we've seen for decades.

 

[bob85]

Donald,
You seem to have the wrong idea about what Henry's graphs are indicating,
And the wrong idea about what i said about the about the mesh cone,

Henry's chart shows the signal strength received at 30km from the transmitter at a receiving antenna 10mtrs above the ground using various transmitting antennas at different heights above ground at the same bottom height,

It shows that as you raise the antenna further away from ground the advantage of the longer antenna is reduced,
There is no +/- 2db wild swing due to mast or coax currents,

quote "All antennas were “ideal” no losses and no other influence"

You told us that your tests where done using a 10ft pole which is
1 wavelength at 98mhz where you told us you last tuned your collinear,

The chart shows that at 1 wavelength above ground the vector has a 2db advantage over the dipole,
Which is what you claim your Dominator shows in your tests,

If you start with a stock sigma or old vector you can tune it to provide more signal on the horizon just like we claimed for years,

Im pretty sure cst will show the H-field from any currents flowing on the outside of coax or a mesh cone acting like coax,

When the Dominator is adjusted correctly for best balance at the top of the 1/4wave cone there should not be much current on the mesh,

in order to have full current flow you would have to shorten the radiator above the cone to 1/4wave like a coaxial dipole,
1/2 wave is as far from that situation as possible,

2dbd freespace is not possible unless you adjust the laws of physics as you adjust the antenna,

As for you finding it somewhat funny that i convinced you to join the forum to defend me against the j-pole camp,

I think your first post on the forum sums up how and why you joined and how you thought the antenna worked,
http://www.worldwidedx.com/threads/avanti-sigma4-an-alternative-view-point.31799/page-2

I bit my lip over the PHAZOR pic you shared with us,
Yes Henry's working collinear did look way too short,

quote from the x-files

"The Truth Is Out There"







.

 

[Shockwave]

I didn't even see Henry's chart. As soon as it became clear he was going to contradict 15 years of in field experience, I stopped reading his article. Although if there is a photo of the actual Sigma design antenna he used for testing, I'd love to see this to determine if he fixed the half dozen errors that were obvious enough to spot in the first photo.

I emphatically disagree that height has anything to do with the performance we see on VHF, I mean we are already at 10 wavelengths in height in many of my applications and DB already confirmed another 1/4 wave doesn't do diddly here but you keep going back to it. He has confirmed that he can also manipulate the radiator length in the models to make noticeable improvements in distant gain on the horizon but just about no one even commented on it.

You're now saying that the "right" wavelength mast can add up to 2 db to the antenna but other multiples of that wavelength cannot negatively impact gain? That's not what we see on other antennas like the Antron 99 that can be badly effected by CMC so how can we change all the rules today on the Sigma?

You're also implying that a solid cone should not effect the performance characteristics of the antenna from the theory of individual fields on each radial. I agree that a solid cone does not effect performance but I totally disagree that performance would be the same if there were independent fields around each radial with the type of interaction Henry claims.

Again if any of this new theory lined up with actual results you would think we might be able to find at least one broadcast client who was pist off enough to make a negative comment online. It takes a lot more to impress clients enough to take the time to go online and profess noticeable improvements over a dipole or J-Pole like you find with complete names on my Website testimonials. Better yet these can also be found from totally independent sources posting in broadcast forums like KOLG did.

To me it's like I'm sitting at a red traffic light and you all are telling me the light is not red and to just go. I don't see it as productive anymore and my better half is questioning me as to why I waste so much time here. If you want to ignore years of results or the fact DB can productively alter the pattern in his models, my efforts are done for now. Keep in mind if you ever find someone I've worked with who agrees with this nonsense, they can send their antenna back to me for a complete refund and go back to a dipole anytime. Good luck in your efforts.

 

[Henry HPSD]

Donald,

Last time, could you....

Please stop making non productive remarks which are trying to put me or anyone else in a bad spot light for which you have no right to do so.
Please remain with facts instead of assumptions.

Kind regards,

Henry.

 

[Shockwave]

Henry, I see nothing in my previous post that could be considered negative personal remarks. What you just requested of me is all I've been asking from you for over a month now and haven't seen you post very many facts at all that line up with the results we see regularly. I'm actually quite surprised you've not been able to replicate a single thing countless users have been bragging about for years.

Perhaps posting a photo of the actual Sigma model you constructed might reveal some of the deficiencies you're experiencing? I know there were several very obvious ones in the first photo you posted for the 4 wire test. I'm guessing you won't consider this option but I've offered anyway just in case you really want to try everything you can.

 

[Henry HPSD]

But I already did Donald.
You seem to have stop reading it, if you could be so kind and read it..
You will find that it is actually not "my" theory...but it is antenna theory.

Now, I will answer any question you have...but I ask you to read it...as apparently you havnt.
I encourage you to find faults...
I encourage you to ask question where things are not understood.
As an "author" I of course need to "defend" my article..
And i will.

I also encourage you to answer a few of my questions which i have asked.
That would be the correct thing to do al you are a manufacturer
A manufacturer who claims:
5,15 dBI
collinear theory
confined currents in cone.
and is verified in field work by several.
etc..

So,...please answer a couple of my questions provided.
And Ill be more than happy to answer yours.

Kind regards,

Henry

 

[Henry HPSD]

Owh and almost forgot...
But i dont think ill be around tomorrow...possible Thursday evening again
(evening here is your time now)

So, please find "faults"...or please ask a questions for verification
Or please start explaining your claims besides your interpretation of the CST plot.
Thank you.

Kind regards,

H>

 

[Shockwave]

Sorry Henry, antenna theory does not dictate that there must be 4 individual radial fields that are totally cancelled in the far field except for 0.1 dbd worth. That is absolutely your theory and the first one of its type applied to this design. I'll also suggest the theory is exceptionally weak in that it lacks any credibility based on consistent results which are in complete contradiction. Although I will look at your latest antenna used for this test when I have a chance.

PS: I'm still boggled by the "theory" that one length of mast can produce a 2dbd gain but no other multiple of mast length can detract from the gain? That doesn't even come close to making a bit of sense and sounds like you're talking out of both sides of your mouth to me.

 

[Henry HPSD]

Hello Donald.

wheter or not it is 3..4..5 ..6 etc..
It doesnt really matter, eventually the density will be so tight it will become a "shielded line" (coax)

If you have a open transmission line (lint line)
You will have two currents..
You will have two Magnetic H fields
And they will be cancelled, that is antenna basics ...
Thats too basic for anyone with serious interest in antennas not to know any book will tell you that.

Please look up "cage line"
Which is a method often used in HF broadcasting to supply large arrays with immense powers.
Now since you are in the broadcasting you are probarbly familiair with them ?

Now...do you think ...they would like to radiate 500 KW from such a line ?
No of course not...

They carefully design it in such a way all is cancelled.
They carefully construct it in such a way ...nothing comes close to it.
(as there sure is an magnetic H field)

Sometimes they have "bows" around them...that is for impedance control /adjustment. ...now...please notice there is perhaps 500 Kw on that line.
But the "bow" doesnt touch it...and still has influence...
Why ? cause we are altering the magnetic H field.
(ps bow i mean is not on picture...unable to find it...ill do a search..)

Oke end of my lesson...

ps for the 8th time. answer one of my questions. ....

 

[Shockwave]

You know that if that 500kw stations antenna were not balanced, there would be significant radiation on that transmission line. What I think you all are overlooking is the fact we don't need close to equal radiation from the cone to realize the gains we see. The gains we see in the field are most likely not the complete result of collinear action and have much more to do with how the TWO fields can be manipulated in such a way that places more energy on the distant horizon. The second current or field does not need to be nearly as strong as the main field in order to have this effect. It's really not as impossible as it appears you'd like it to be.

 

[Henry HPSD]

PS: I'm still boggled by the "theory" that one length of mast can produce a 2dbd gain but no other multiple of mast length can detract from the gain? That doesn't even come close to making a bit of sense and sounds like you're talking out of both sides of your mouth to me.

Donald...saying that i talk out of both sides of my mouth is something i what I consider coming close to an insult.
Of course i now consider you are saying it "happy" in a joyful conversation..

Oke...here we go...

As a broadcast antenna manufacturer im confident you know that the longer the radiator becomes the more gain we can have from that radiator.

We all know a 3/4 wave produces more gain then a halve wave.
But sadly the lobs will be pointed more along the ax of the antenna forcing the radiation in the sky there for demolishing the gain where we want it.

That radiator can be anything as long its a conductor.

Image a vertical halve wave dipole.
Take away the bottom part...and insert a car...
We have made our ground-plane antenna which still exist out of "two parts"

Now...if we place a vertical antenna on top of a mast...
that mast can also become a radiator...making the antenna longer and in most cases making the pattern worse and there for detract gain from where we want it.
In some cases bad antenna depend on such effects..
Like the polyester boat antennas where the coax needs to be a specific length.

And you know what...we dont evan have to make that mast "dc grounded"
The most obvious example:
Imagine a mast and the dipole next to it.
The dipole have more "coverage" in the direction it is pointing and will have "FB" in the direction of the mast.

It is clear that a mast can detract gain but can also provide beneficial gain.

Anyway...i do apologize bed time here...i hope to find some time tomorrow but probarbly not...thursday it is.

End of lesson.

pse answer my questions...(9th)

 

[Henry HPSD]

Donald..

are most likely not the complete result of collinear action

We are almost there...Im proud of you thumbs up !

ps...and yes....but the sad thing is...
as soon as we have "radiation" from the cone....the antenna will become more a 3/4 wave radiator.
providing higher gain...but upwards...there where we do not want it.

Under perfect conditions maximum gain would be in the order of 3 dBi or so...and that is without the cone as the radiator can "fully" radiate" as there is no phase shift going on.

So...in order to have maximum effort from the vector you would need to make the antenna in such a way the cone "sees" a electrical halve wave on top...then max will be send in a 0 degree angle..most beneficial for "distance horizon communication.

Really of to bed now...73s.