Homemade Sigma 4 11 meter base antenna

[Shockwave]

Shockwave,
I am not a member over on eham, but I was reading your discussion with them about the V4k.
I don't know whether this quote of a post to the thread says the same to you on a single thought as it does to me, but it seems to say that the point is confirmed by this contributor that the out of phase currents within the cone are contained, and those on the outside of the cone are in phase with those on the upper 1/2 wave vertical. While he goes on to say that he does not see the lower cone in-phase currents accounting for much in the way of far field support for additional gain, I think that an opportunity to respond to the fact that despite a lower radiation strength from the cone there is still that undeniable reality that the out of phase currents are NOT a factor that contributes to a very high primary lobe usually seen from a 3/4 wave vertical, and that the radiation from the cone being in phase can only reinforce the toward the horizon gain of the 3/4 wave antenna as a whole.

I think this point, whether here in this thread, and in other places I've read, seems to be spoken to, but not appreciated.

Marconi likes to say that he sees only the additional height of the antenna from the feed point up as the only reason the V4k is a better antenna than a shorter vertical, yet this defies the long standing accepted proposition that the longer than 5/8 antennas have a single fatal flaw of casting their primary lobe too high into the stratophere to constructively contribute to communications on planet Earth due to the lower out of phase 1/4 wave where it matters - additional gain toward the horizon..

The V4k has resolved that issue. If that one solution has not contributed to the superior gain of the 3/4 wave antenna being cast toward the horizon regardless of how much additional radiation the lower in phase 1/4 section adds, then antenna theory older than any of us here on the forum must be cast aside as historically inaccurate, and a 3/4 wave antenna does not have superior gain over other shorter lengths.

Can we really have it both ways, or am I missing something that doesn't make these views self-conflicting and contraditory?
Just thinking out loud.

In fairness I have an Eznec model Marconi did for me of the V4k when I was discussing with him the Merlin, a 5/8, and the V4k at the same current maximum height. The V4k in his model was the least impressive of the three. However, there is nothing in my experience with the V4k that supports that Eznec modeling result. I am only just learning with the free Eznec program to model, and there is more I have to learn than I know, so I have no criticisms of the model.
However, that result only reaffirms to me that Eznec is likely deficient in its ability to accurately model this antenna.

I also have been under the impression that when comparing antennas at the same current maximum they have so little difference in sub-points of gain that they are practically identical. I accept this due to my personal testing of the 1/2 wave, the 5/8 and the Merlin against each other in this way. However, what I keep on the horizon of my thinking is that because there is this lower out-of-phase portion of the 5/8 wave, and that the Merlin, like the Starduster, has such a steep angle of droop in the radials that it presents itself as a 1/2 wave potentially, what we have is essentially three half-wave antennas being compared to each other. Eznec confirms this possibility.

Because the V4k eliminates this out of phase current as a player on the lower 1/4 wave of its 3/4 wave total length, and redistributes its current as being in-phase along the entire length, I tend to agree with the CST model, my experience, and the experiences of Bob and Shockwave, as well as the comments of Cebik regarding the weakness of Eznec to this antenna, and its non-apparent colinear nature. No other vertical has produced the results of this antenna for me.
There may be others, but I have not flown them, yet.

Homer, I'm obviously in agreement with what you've said here and mostly agree with what you quoted from WB6BYU. The key difference is I've seen the gain improvement in the field over a 1/2 wave too many times in 15 years to not notice it is significant in the fringe area where you are working with weak signals. Many times this can be the difference between no copy and full copy. I'm pleased to see others like yourself can replicate my experiences. None the less, the debates still keep going.

 

[Marconi]

I hope you guys don't think I'm trashing the Sigma4 design by my questioning how it works. For me, the excellent performance is not in question. I've likely posted more anecdotal antenna reports than all of you guys put together, but this is not what my words are all about here.

I find the Sigma4 among the best performers I have. But, I don't think its perfect to the exception of all others, and I do see advantages for other antennas I test while comparing to my Sigma sometimes.

Regarding the idea for real world testing, I don't see any antenna I have dominating 100% of the time. My arguments are about how it works.

Marconi likes to say that he sees only the additional height of the antenna from the feed point up as the only reason the V4k is a better antenna than a shorter vertical, yet this defies the long standing accepted proposition that the longer than 5/8 antennas have a single fatal flaw of casting their primary lobe too high into the stratophere to constructively contribute to communications on planet Earth due to the lower out of phase 1/4 wave where it matters - additional gain toward the horizon...[ /QUOTE]

Homer, I have always understood the advantage for the taller CB antennas we use as noted on the following reference for vertical antenna gain. I think this is an old standard that has probably stood the test of time for gain...when we considered its meaning correctly as intended, and as noted in the attached captions, which are often totally ignored, as to what the two charts indicate.



I also believe the idea for antenna's with a raised 1/2 wave radiator like the 5/8 does make the modest increase in gain over the 1/4 and 1/2 wave antenna we see above...even if the bottom 1/8 wave portion of RF is canceled out. I don't believe for one minute that the 5/8 wave has a fatal flaw in this regard, and it does not produce a primary high angle lobe as a result, like you suggest.

If you will note in the first chart of the diagram above you'll see there is, like you say, a high angle lobe produced, but it is not the primary lobe by a long shot.

You can also see in the second chart that the peak for gain is at little over .6λ. Thus we see the antenna with higher current maximum shows the maximum gain.

I don't question that a 5/8 wave produces an out of phase portion at the bottom of the radiator that is of little value for gain, but where did you get the idea about a 5/8λ having a fatal flaw that results in a higher primary gain lobe?

I do believe that the 3/4 wave radiator with slanted up radials responds nicely for match, and in this case overcomes its natural production of an otherwise high angled primary lobe when using horizontal radials. But IMO, these features for the Sigma4 design simply accomplishes similar result as the 5/8 wave...by raising the top 1/2 wave element (current maximum) even higher...thus we see some additional, though modest gain over the 5/8λ antenna, and the whole antenna looks to radiate with a little bit from the bottom.

Even Bob has indicated in a recent response that he doesn't know how much the bottom adds. And I concede that it does look to radiate a little bit in both my model and the CST model.

In my real world experiences I too have seen, many times, one antenna working better by enough that I can tell just operating my radio. Sometimes I see conditions change different antenna responses in minutes or over some other period of time, so I have to consider this when I evaluate my antennas, and I tend to consider such responses as an exception. I think you guys probably see similar things happen at times too and unless we can duplicate such exceptional contacts most of the time...I don't count them. I have talked over 300 miles before, Oklahoma City, far West Texas, and New Orleans, but I consider all that due to conditions and not my antenna.

 

[HomerBB]

I hope you guys don't think I'm trashing the Sigma4 design by my questioning how it works. For me, the excellent performance is not in question. I've likely posted more anecdotal antenna reports than all of you guys put together, but this is not what my words are all about here.

I find the Sigma4 among the best performers I have. But, I don't think its perfect to the exception of all others, and I do see advantages for other antennas I test while comparing to my Sigma sometimes.

Regarding the idea for real world testing, I don't see any antenna I have dominating 100% of the time. My arguments are about how it works.

Marconi likes to say that he sees only the additional height of the antenna from the feed point up as the only reason the V4k is a better antenna than a shorter vertical, yet this defies the long standing accepted proposition that the longer than 5/8 antennas have a single fatal flaw of casting their primary lobe too high into the stratophere to constructively contribute to communications on planet Earth due to the lower out of phase 1/4 wave where it matters - additional gain toward the horizon...[ /QUOTE]

Homer, I have always understood the advantage for the taller CB antennas we use as noted on the following reference for vertical antenna gain. I think this is an old standard that has probably stood the test of time for gain...when we considered its meaning correctly as intended, and as noted in the attached captions, which are often totally ignored, as to what the two charts indicate.

View attachment 9251

I also believe the idea for antenna's with a raised 1/2 wave radiator like the 5/8 does make the modest increase in gain over the 1/4 and 1/2 wave antenna we see above...even if the bottom 1/8 wave portion of RF is canceled out. I don't believe for one minute that the 5/8 wave has a fatal flaw in this regard, and it does not produce a primary high angle lobe as a result, like you suggest.

If you will note in the first chart of the diagram above you'll see there is, like you say, a high angle lobe produced, but it is not the primary lobe by a long shot.

You can also see in the second chart that the peak for gain is at little over .6λ. Thus we see the antenna with higher current maximum shows the maximum gain.

I don't question that a 5/8 wave produces an out of phase portion at the bottom of the radiator that is of little value for gain, but where did you get the idea about a 5/8λ having a fatal flaw that results in a higher primary gain lobe?

I do believe that the 3/4 wave radiator with slanted up radials responds nicely for match, and in this case overcomes its natural production of an otherwise high angled primary lobe when using horizontal radials. But IMO, these features for the Sigma4 design simply accomplishes similar result as the 5/8 wave...by raising the top 1/2 wave element (current maximum) even higher...thus we see some additional, though modest gain over the 5/8λ antenna, and the whole antenna looks to radiate with a little bit from the bottom.

Even Bob has indicated in a recent response that he doesn't know how much the bottom adds. And I concede that it does look to radiate a little bit in both my model and the CST model.

In my real world experiences I too have seen, many times, one antenna working better by enough that I can tell just operating my radio. Sometimes I see conditions change different antenna responses in minutes or over some other period of time, so I have to consider this when I evaluate my antennas, and I tend to consider such responses as an exception. I think you guys probably see similar things happen at times too and unless we can duplicate such exceptional contacts most of the time...I don't count them. I have talked over 300 miles before, Oklahoma City, far West Texas, and New Orleans, but I consider all that due to conditions and not my antenna.

First I'd like to apologize for what appears to be me calling you out on something when I only wished to point to a participant in the discussion who had been willing to voice a particular point of reference for what I was trying to say.

Most of your response, however, I can not respond to because you failed to read what I actually said:

Marconi likes to say that he sees only the additional height of the antenna from the feed point up as the only reason the V4k is a better antenna than a shorter vertical, yet this defies the long standing accepted proposition that the longer than 5/8 antennas have a single fatal flaw of casting their primary lobe too high into the stratophere to constructively contribute to communications on planet Earth due to the lower out of phase 1/4 wave where it matters - additional gain toward the horizon..

The V4k has resolved that issue. If that one solution has not contributed to the superior gain of the 3/4 wave antenna being cast toward the horizon regardless of how much additional radiation the lower in phase 1/4 section adds, then antenna theory older than any of us here on the forum must be cast aside as historically inaccurate, and a 3/4 wave antenna does not have superior gain over other shorter lengths.

It was not a 5/8 I was talking about, but antennas longer than that. I considered the .64, but the length of 0.015 difference is so neglegible between the .64 and the .625 that I have seen no detectible performance differences between them.

I will be clear on one thing, I do not attribute the advantages of the V4k to merely having the current maximum higher, but also to the design that causes an entire 3/4 wavelength vertical to be radiating in phase.

The performance several of us have seen from the V4k antennas has been repeatable, and can be duplicated by others, and appeared with no other antenna I, and as they've said, they have seen.
That is the center of my point.

 

[Marconi]

No Homer, it is I who must apologize.

Even though we might still disagree on how the Sigma4 works to produce good low angle gain, I must apologize to you for reading your words wrong.

I see it clearly now that your words were saying...you were referring to antenna's longer than 5/8 wavelength. Sorry!

 

[BOOTY MONSTER]

Tagra BT-104, the best 24-30 MHz, 7/8 J-pole antenna, ever built - YouTube

 

[HomerBB]

No Homer, it is I who must apologize.

Even though we might still disagree on how the Sigma4 works to produce good low angle gain, I must apologize to you for reading your words wrong.

I see it clearly now that your words were saying...you were referring to antenna's longer than 5/8 wavelength. Sorry!

No sweat. What's a misunderstanding among friends.
To make it up, you're invited to supper tonight.

 

[HomerBB]

Booty
The fellow in the video certainly likes the antenna, but like others even he appears ignorant of the antennas properties. He calls the cone the tuning basket. Put the antenna in the air without the Gamma Match, which, of course he used, and no amount of begging pleading, or bribing a crooked judge will get that antenna tuned.

But thanks for sharing it. It is a beauty.

 

[Lil'Yeshua]

My Sirio Vector 4000 was just delivered. Gotta wait to get off from work a nd see this baby!

 

[HomerBB]

Sweet.

 

[Marconi]

No sweat. What's a misunderstanding among friends.
To make it up, you're invited to supper tonight.

Sorry Homer, I can't travel for 7 more days, I had a Coronary Artery Angioplasty procedure done yesterday morning, plus I can't find my shoes.

Thanks

 

[BOOTY MONSTER]

My Sirio Vector 4000 was just delivered. Gotta wait to get off from work a nd see this baby!

hope it hold up to your weather conditions there .

 

[Lil'Yeshua]

Just got the Vector 4000 today. Just got home from work. The package is damaged I looked through the puncture and all I see so far is a 2" mild scrap on one if the vertical elements

 

[Lil'Yeshua]

The puncture

 

[RADIOOMAN]

Was it handled by UPS or someone else?

 

[Lil'Yeshua]

Was it handled by UPS or someone else?

UPS. I'm fixing to take it inside and check out the parts