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Bob and SW, while you two argue high angle lobes, phase, and stub respondes, I'll ask a question, and make some comments.

 

Do you both figure there is somehow constructive collinear type phasing going on in the Sigma4 at the top of radials cone that produces the good results we see in the Vector/Sigma design? Is this what you both are trying desperately to prove?

 

For me this idea is based solely on a few undocumented words from a dead man, and can't be explained further from his point of view. What if this affect we see going on with the Sigma design is just a simple response associated with raising the radials, as apposed to something magic or mystical going on.

 

I think, I see, in my modeling that phasing two elements that are not electrically equal, tends not to show successful collinear type results. I'm not saying it can't be done, I'm just saying in my limited modeling experience...I don't see it. I see the model that Sirio presented, but I can't say for sure I understand fully what I see. It does look to me that the bottom cone is producing rf in phase that is contributing with the top, but it does not explain why or how it does that.

 

I also think what I see by pushing the radials up on a radiator .625 wave to .75 wave is the configuration itself is pushing down on the typical high angle lobe noted for all 1/8 and 1/4 wave radiators. IMO, this setup very simply allows the 1/2 wave radiator to be raised up higher than the .625 wave radiator as compared. So, therefore I believe this is the reason the Sigma design shows a modest increase in gain at a lower angle to the horizon when compared, and there is nothing special really going on. If you check out some of the models I posted over time I think you will see this modest difference indicated as well, and that is not just words.

 

I think SW is suggesting to Homer that raising the radials on a .625 wave will not produce similar results to the .75 wave, because there is not enough current flowing in the bottom 1/8 wave portion of a .625 wave radiator. I don't claim to understand much of SW words, but my models do not support this notion. I see the same pushing down of the higher angle lobes with the .625 wave...as I see with the .75 wave radiator.

 

I think you guys are trying to justify that the bottom of the Sigma is contributing constructively with the top of the Sigma via a phasing idea that does not exist, or at the very least is arguable. IMO, the idea of raised radials simply shows us that raises radials push the physical top 1/2 wave radiator up higher...than the top 1/2 wave for the .625 radiator. I would venture a wild guess here, that if you raised a 5/8 model up equal to the current node of the Sigma4, the results on of near the horizon would be similar or exactly the same, and that might also include the lower 1* in angle as well, seeing as height has such an affect on TOA.

 

I think I can demonstrate this idea with models Homer, if you want to see something besides just words. This said, I still remain open for someone to produce some real evidence in understandable English to the contrary...other that just words.

 

 

I will email Homer the results of these two models along with a brief explanation as I understand the work, because I think he is asking for such information. We will see if it makes and sense to him and if it does, then I'll post the project. Just let me know Homer. I will wait for your request or your denial.

 

In my opinion, regarding the Sigma4, I don't think it matters enough whether I'm right or if Bob and Shockwave are right, the Sigma designed antenna proves, by performance, that the act of raising the radials up works, solves the problems typically associated with radiators that are 3/4 wavelength, lowers the angle of maximum radiation by 1* degree compared to other designs at some heights, and works very well mounted low to the Earth...if mounted well into the open.