[VHFcontesting] Loop Yagi theory

[Bill Olson]

yeah, like a "cubical quad", which is a full wave loop element .. what makes it different from the HF quad you normally think of is that all the low impedance points are all tied together to ground (the boom)..


you could also think of it as a big fat folded dipole..


back in the original Down East Microwave days I *had* experimented with floating the elements and feeding it in both planes out of phase to actually get circular polarization, but the whole thing got pretty messy and I gave up on that.. There WAS some interest for satellite work..


Anyway with the manufactured antennas you get these days, with the semi-rigid feedline that goes through the driven element vertical the polarization is horizontal and vice versa.. always linear though..


bill


________________________________
From: VHFcontesting <vhfcontesting-bounces at contesting.com> on behalf of Zack Widup <w9sz.zack at gmail.com>
Sent: Monday, October 3, 2016 6:12 PM
To: VHF Contesting Reflector
Subject: Re: [VHFcontesting] Loop Yagi theory

It's basically the same idea as with a quad antenna. A loop (either
circular or square) fed at the bottom or top has current peaks at the
feedpoint and opposite side of the quad or loop, and voltage peaks at the
side points (90 degrees to the feedpoint). This is similar to a horizontal
dipole antenna, which has horizontal polarization.

There's more to it than that, but that's the basic idea.

73, Zack W9SZ


On Mon, Oct 3, 2016 at 12:38 PM, Mark Spencer <mark at alignedsolutions.com>
wrote:

> Hi does anyone know of a web site that explains why loop yagis are
> horizontally or vertically linearly polarized ?
>
> I recently gave a presentation to a local club on VHF and up weak signal
> operating and when I showed pictures of one of my 1296 loop yagi antennas I
> was asked if they were circularly polarized.   I don't think my answer that
> they were sold to me by the manufacturer as being horizontally polarized
> and other local hams use similar horizontally antennas, and as a result I'm
> able to make contacts with them was quite what the audience was hoping for
> (although from the perspective of getting on the air and making contacts I
> believe it was a reasonable answer.)
>
> The next time I give a similar presentation it would be nice to point
> people to a web site that explains this in detail (:
>
> Thanks in advance for any suggestions.   (Some google searching didn't
> turn anything up and reading thru the loop yagi section in my arrl antenna
> books also didn't give me an answer.)
>
> 73
>
> Mark S
> VE7AFZ
> _______________________________________________
> VHFcontesting mailing list
> VHFcontesting at contesting.com
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The VHF Contesting Reflector is designed to be a place to discuss all aspects of contesting on frequencies of 50 MHz and above. We hope to generate discussions of any ...