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Thank you! I believe I see it now. A 50Ω direct-fed 3/4 wave which is folded so that the lower 1/4 radiates in phase with the 2nd 1/4 wave which creates the bottom half of a 1/2 wave with high current at the 'center' feed point, high voltage at the ring, high current at the center bar and high...

Worst case scenario, you have more than $25 worth of usable project aluminum! :ohmy:

Though the design is still somewhat of a mystery to me, I have a feeling you will see an overall loss in performance in comparison to the 5/8 -.64, not only because of the AP design's inherent handicap of loss of overall height above mast, but because when I tried one out (many decades ago) I...

Can do. I'll measure and post them later this afternoon, if that's alright.

C0pper is too soft, heavy and expensive. You'll love yourself for choosing aluminum.

Right-o! Say Yolida, Scott

Hi Norm, OK, I measured what I could but there's some sort of double rubberized cover which doesn't want to open and all I could do is try to figure out the number of turns with my thumbnail. First the coil is about 1 1/8" in diameter, and it appears to have only about 3 turns. The entire...

:oops: ...I think we forgot this is an antenna thread. :D OK, so, I didn't get it up today but... Uh, I mean, I didn't get to erect the Sir... Uhm, I'll be installing the new Sirio on the P500 mast & coax tomorrow, I didn't get it done today because I was lazy, and I enjoyed it! :p

I really don't appreciate this, Dave... Next thing you know, you'll be trying to tell people that it's really alright to use BASE SWRz in the MOBILE!

Yeah, yeah... rub it in. Now you know why I have to use an amplifier

Nicely done, Marconi! One thing, and I don't know if it will affect performance, the radials are 8' 9" plus about 2" of mounting bracket, plus their average diameter of .5", so I'd enter them as 108.6" @ 27.2MHz. Also, I calc ~278" for 27.2MHz. - I'd like to know the 10° gain factor on the...

What's the myth part, -that adding 6.5" to the length of a 5/8 (enough added length to force a retuning of the matching network) has any beneficial effect at all on the signal? At least it's an additional (2.5%) of capture area which, if nothing else, should help receive. George, I didn't...

Hey Bob, what were the results of Mack swapping his Wolf.64 for the Vector, and do you know where is that post?

OK, guys, now you know that was tongue-in-cheek, right? :thumbup1: Anyway, I 'bout fainted when I saw the $375 AUD price for an IMAX and radials kit. YIKES! You could get a couple of SGMs there for less and have a superior performing antenna. Marconi, Have you an interest in a P500? :biggrin...

Since it's the Christmas season I can get away with posting a, "Bah, HUMBUG!" to your side by side comparison. :biggrin: I'd rather see you live with the Sigma4 AS YOUR ONLY ERECTED ANTENNA for a week or so, all the while notating signal strength from as many stations & directions as possible...

Replaced the original 96" IMAX top with a 6" longer fiberglass whip from an old Shakespeare Big Stick and retuned the rings, saw ~.5 S-units improvement. Also added a single .64 radial, but I like your idea of the 102" at the base. How did you get the Maco GP kit to fit, or is it designed for...

Well, I do wonder how it could simply remove the unwanted out-of-phase current? Cancelling it seems probable, but wouldn't they cancel one another in doing so? It seems the bad current would cancel the good current. You can't simply expect energy to vanish, it has to go somewhere so I'd expect...

MYTH? There's no myth, George, - everyone knows the .64 is believed by a small minority to invariably outperform the conventional 5/8 in rare circumstances and at specific, but unknown distances! :D What really has me by the proverbial balls is the added receive gain over my "Beloved"...

My inspired guess, (if anyone really gives a rip... :wink:) is that the differential currents in the lower ¼ should cancel, leaving the upper active part both well elevated above what one would get from a standard bottom-fed 5/8, plus, (and due to the cancellation of the lower ¼ wave currents)...