In a message dated 5/13/01 4:48:46 PM Eastern Daylight Time,
thompson@mindspring.com writes:
> The problem with loops as parasitic elements is
> that they have a low Q (broad bandwidth response)
> and thus in practice fail to live up to the published gain figures of
> Lindsay and W6SAI. This can be overcome by using driven elements
> as noted by W6PU (ex K2DGT) some years ago in QST. Fred, K3ZO has found
> that the W6PU design can be improved and he has done so. The problem is
> again its more complex that a yagi to achieve.
Interesting that W4RNL is claiming that Quad loops have HIGHER Q than a Yagi
(halfwave) elements. I was led to believe by W6SAI and other's claims that
Quad loop has lower Q. That is what I reasoned in designing Razors - the Quad
- Yagi arrays. Looks like time to do some measurements (worth thousands of
"calculations") to see what is really going on. Now with modeling tools it
opens new area for investigation. I have been playing with some models and
trying to optimize some of my old designs. There is some discrepancy, some
measurements will have to be done to verify the accuracy of modeling in the
software. Reading W4RNL material, I have been pleased to find that some of my
old 2m modeled designs seem to beat his software modeled designs. Both seem
to perform better than "inferiority" implied by W8JI's "gospel". Plus some
designs allow dual polarization and pattern filling unobtainable with other
(Yagi) configurations.
>.....K6YNB (now K6NB) came up
> with the Quagi as another effective way to utilize the loop in a parasitic
> array.
>
That's, N6NB, who basically replaced reflector and driven Yagi elements with
Quad loops in VHF Yagis. VE3BMV Razors (Quagis) are optimized Quad - Yagi
arrays done from scratch on 2m models outperforming any other designs on the
same boom length.
Yuri, K3BU
back from sunny Arizona
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