Avanti Sigma4: An alternative view point

[CDX-007]

Well, I meant an active 1/2 wave over another active 1/2 wave by making something 1.5 total = 3/4 x 2 where the radiation from the center 1/2 is canceled and the top 1/2 + sleeved 1/2 would be in phase, but now that I ponder it, if broken & center-fed it would display inverted phase so the bottom of the sleeve would begin to radiate 180° out of phase (270°-90°) from the top 1/2 wave (90°-270°) so no good.

It may not work right unless a gamma is used, depending upon the phase angle being introduced at the gamma feed point.

Do you recall what were the radials length and the ring diameter?

 

[Shockwave]

At 98 MHz I've experimented with radial lengths from about 20 inches to 40 inches. The loop circumference was varied about the same amount. I haven't tested 1/2 wavelength radials with a longer radiator yet. I've had very good luck with the radials and loop circumference right around a physical 1/4 wavelength. If you're looking for a good starting place on 11 meters here is my best suggestion. Radials at 106 inches. Loop circumference at 94 inches (you could try the full 1/4 wave). Radiator length about 28 1/2 feet, straight with no cadge on top. Models of this antenna have been marketed for 11 meters using the old 90.5 inch radials, 94 inch loop, and radiator from about 27 to 30 feet.

 

[CDX-007]

Shock, is that 28.5' total or minus the 16" of lower mounting tubing beneath the radial/ gamma hub?

 

[Shockwave]

Shock, is that 28.5' total or minus the 16" of lower mounting tubing beneath the radial/ gamma hub?

From the connector hub to the tip of the main radiator, not counting the mounting space beneath.

 

[HomerBB]

Nothing earth shaking going on here. I've not been able to get back to the old 5/8 wave for any work to make it a worthwhile comparative to the Qv4k. If I'm given enough time soon I'll get to it. However, as a satisfactory aside I shared a little ratchet jawing session with a local friend who runs an Imax 2000. We are perhaps a 1/4 mile apart. Of course we were doing fine talking to each other. What was fun for me was a truck driver broke to ask us where we were and what we ran. In the past the other fellows Imax gave me a run for the money sometimes receiving what I couldn't adequately pull out, but from the hills southwest of us about 15 to 18 miles out as the driver drove away from us with his audio/signal moving up and down with the terrain I could hear and converse with the driver using my Qv4k when the other station could not. At the point that the other station said he was having trouble pulling the truck driver out and let the driver go I was having no trouble what so ever. I realize this distance is negligible to many, but understanding the nature of things here in the heart of the Ozarks makes this kind of mobile to base transmission significant. Nevertheless, the point for me here is the clear out performance of my Qv4k over the previously superior Imax 2k in this unplanned set of circumstances. BTW, both our antennas are at the same elevation above ground.

Fingers are crossed for more hopeful indications of this antennas superiority over previous types of omni-verticals I've used.

 

[CDX-007]

Homer, are you making the point that his Imax has outperformed your 5/8 in the recent past when the 5/8 was as high?

That is a good 'real-world' account.

 

[HomerBB]

The months I had my latest 5/8 up (that I reworked into the Qv4k) he hadn't moved here yet so I was unable to compare those two, but I did have up a couple different half waves and some dipoles of various configurations that his antenna easily trumped. Also the 2 element Quad I gave away this past Spring was up when he was most active and I naturally had to turn it toward anything he heard better than I did. I did have the 5/8 up a little while at a lower elevation right before I began to rebuild it into the Qv4k, but he has been out of state, and I had no chance to go head-to-head with him lately. My point was that I experienced personal satisfaction from trumping his antenna with such a clear margin of better performance. I am trying to get the older homebrew 5/8 up to the standard of the last one (time and the parts being put into the Qv4k have been impediments to my progress), and then hopefully I can pit both it and the Qv4k against each other and his antenna. It will have to be soon as there is someone in need of the 5/8 when I get it done so I have already given it away.

 

[CDX-007]

Homer, I envy your ability to provide so much clear information in such short paragraphs... I should have stayed in Tech Writing class. :blush:

OK, well, I respect a good head-to-head test, same pole, coax, height, location etc., but I also respect daily living experience, so if you have gotten used to the performance of the Qv4k and could pull it down, (after jotting down some average signal strengths of local operators) and replace it with the 5/8 for a week or two, I'm certain you'd have an almost immediate preference, as I know I get a 'feel' for an antenna and am able to quickly notice losses when I hear someone I'm used to hearing with a certain static or tone quality and they are either louder & clearer or not so clear.
I'd like to hear you try such, but I don't know if that would be far too much hassle with that interesting home-brew tower of yours.

 

[jazzsinger]

Must be very satisfying to know something you built yourself outperforms one of the most hyped antennas of all time.

Hype certainly sells stuff, but it don't make it perform any better.

The months I had my latest 5/8 up (that I reworked into the Qv4k) he hadn't moved here yet so I was unable to compare those two, but I did have up a couple different half waves and some dipoles of various configurations that his antenna easily trumped. Also the 2 element Quad I gave away this past Spring was up when he was most active and I naturally had to turn it toward anything he heard better than I did. I did have the 5/8 up a little while at a lower elevation right before I began to rebuild it into the Qv4k, but he has been out of state, and I had no chance to go head-to-head with him lately. My point was that I experienced personal satisfaction from trumping his antenna with such a clear margin of better performance. I am trying to get the older homebrew 5/8 up to the standard of the last one (time and the parts being put into the Qv4k have been impediments to my progress), and then hopefully I can pit both it and the Qv4k against each other and his antenna. It will have to be soon as there is someone in need of the 5/8 when I get it done so I have already given it away.

 

[CDX-007]

Must be very satisfying to know something you built yourself outperforms one of the most hyped antennas of all time.

Hype certainly sells stuff, but it don't make it perform any better.

I hope you're not implying there's a better antenna on the planet than the Imax!

Actually, it is my 'A99' if you will... as so many people worship the A99, so I appreciate the Imax for how hard it tries to keep up with the big metal antennas.
I have one up right now and it's continually surprising me with performance which it's inexpensive & radial-less countenance belies.

...but it ain't no Penetrator! :tongue:

I'll never let mine go because I can't think of a better camping antenna!

I wonder if his neighbor will ever replace his Imax with a metal antenna once he tires of Homer stomping him?

 

[jazzsinger]

I hope you're not implying there's a better antenna on the planet than the Imax!

perish the thought,far be it for me to shatter the delusions of the multitudes.

 

[Robb]

I think there are a lot better antennas than the IMAX.

However, for less than a $100 it is impossible to beat it.

That is - if money spent is the measure.

'Bang fer buck'.

The Avanti is an incredible antenna for its price range - from what I can gather that has been posted here,

 

[HomerBB]

To stay on point with the thread, I hoped to show how my antenna fared against my neighbor's Imax. I really like his antenna, as Robb pointed out, and wouldn't hesitate to use and recommend it when appropriate. I like to make them, and these Sigma/Avanti threads have inspired me to tackle a design I may not have attempted without the valuable information everyone has contributed.
I replied to the implied question about how hard it would be to change out the two antennas on the same tower in another thread - tip over tower - wooden homebrew

Thanks on the writing. Hard to respond to that one.

 

[CDX-007]

...I replied to the implied question about how hard it would be to change out the two antennas on the same tower in another thread - tip over tower - wooded homebrew...

I was able to raise it without straining. It lowers as easily, too. I was concerned about the leverage being in the towers favor. Nope, I'm in charge completely. Sure gonna beat wrestling with a long pole from on the house. I'll be able to work on windy days, too!

Excellent! Can we anticipate just such a comparison in the relatively near future?

 

[HomerBB]

Excellent! Can we anticipate just such a comparison in the relatively near future?

Yes, but the older 5/8 needs to be worked up to the right standard. Soon.