And lastly... Even though I went to all the trouble to build one from scratch, my humility is 100% intact so that when he told me that a 5/8 wave GP outperformed them at the test range, it was not a problem... The truth is only the truth and denial will make you waste more precious time than we already do... Learning is what I care to do so it served it's purpose.
i am not 100% sure i am correct about how the sigma works but i am sure of what they can do,
the modified sleeve antenna has all the ingredients and the elements are configured in the same manner as the sigma style, while freecells version is very similar to my own ideas, he falls short of saying what he thinks happens to radiation from the radials, he has stated that the lower portion radiates in the past, his other claims of lower impedance and raised resonant frequency as sleeve to monopole spacing is reduced fits published material on sleeve antennas and what can bee seen in field tests,
me and shockwave claim the same results and use the same tuning method of tuning for maximum signal at distance, shockwave has his cone effect theory where the lower 1/4wave does not radiate but it compresses the pattern, i dont understand it because i cannot find any published material, nor can shockave, he admits its his theory as do i with my modified sleeve monopole theory, the published claims for the sleeve antenna are that it also compresses the pattern because radiation from the sleve is in phase with radiation from the portion of monopole above the sleeve, i am not sure that radiation can be measured in the near field with a simple field strenght meter, while we do not agree on exactly how it works we agreee 100% on how to tune them and what results we see,
the gamma feed allows a wide range of element lengths/transmissionline mode or antenna mode impedance changes while still maintaining a low vswr, it opens up a range of possibilities over the direct fed sleeve antenna,
radiation angle of sleeve antennas is manipulated through relative element length ratio adjustments, if i understand it correctly that alters the phase relationship between currents in the radials and currents in the central monopole, in a similar way changing the phase relationship between dipoles in a 4 dipole array by stagger feeding them with different length coaxial will give downtilted or uptilted radiation angles at the expense of some gain, altering the phase relationship between two or more stacked 5/8waves can also be used to achieve the same kind of beam steering,
from your description the lw150 was too short, in our tests a stock length sigma4 tuned correctly will do exactly what the patent claims, the extended version will do better at distance, shockwaves tests on 11mtrs and the commercial fm broadcast band indicate a further small improvement when using a wider radial angle as noted in the avanti patent,
you can check out shockwaves measurements for his modified vector4000 on wwrf,
my personal feeling is that you will find the best measurements for your location and mounting height by doing your own tuning while observing stable distant signals ( not in dx )
as far as i know the only people that have tuned like i do is shockwave and friends i have had modify their sigma4's, a few guys on 10mtrs also did the same mods after listening to me and claimed better performance but i cannot confirm what they say,
how much improvement over factory tuning?, i gained 1.5 s-units at 60+ miles as seen on a ft990 s-meter and a similar gain on the ft767 s-meter, at closer distances i see a much lesser improvement, that does not mean you would see the same if you used the same radios but it demonstrates a means to significantly change signal strength at distance while maintaining a low vswr, since i doubt we are significantly changing the gain i assume we must be steering the radiation angle to a lower more favourable angle as seen in sleeve antennas designed for different applications,
i am always open to looking at alternative explanations.
Then again, I'm just an old fart who's been running a 3-eared, crappy A99 that's always done a far better job than I've ever needed it to do.
As long as it works for you and you're happy with it, that is all that matters.
I went looking for something that was similar to the Avanti Sigma II (AV-170) I had. Plus I wanted durability; I wanted to erect the antenna and not worry about it. I looked at quite a few before settling on the one I have now. The Interceptor 10K. The only other antenna that I consider a close match was the Wolf .64, just because we do get a lot of lightning in the area.
What is the general opinion on the Avanti Sigma IV (AV 174) omni directional antenna? Still after 25 years I have a brand new one in a box at the attic.
This same debate was going on back in the mid 1980s when 2 of my friends were using the Sigma4 style SALUIT LW150 antennas & I used the original SuperPenetrator. We all use to argue over who's antenna was better & it became a competition thing with radio checks & on air contacts.I could hear & talk just as far as either of them so I wasn't convinced their LW150s were any better than my Penetrator. Years later after relocating I decided to try one & bought what was labeled at the time a Galaxy27 32'ft.3/4 wave @ 6.5db gain. I later bought a newer version of this same antenna that had a corrugated Aluminium radiator.I set this one up high on a hill & it was the best performing antenna I have ever owned. I recently purchased a New Vector 4000 to replace my Maco V58 with. I am anticipating great results with this Improved design & like what Sirio have done. The older models I had were a challenge to hold together in high winds & had to be modified for strength & durability. Beyond all the technical garb that's been said about this design I find it funny that all these years later the debates continue.