[TowerTalk] quad user report

[Lane Zeitler]

I very casually mentioned in my X-7 post today that I'm using a homebrew 3
element quad. Several of you have asked me questions abt it so here is a
copy of what I sent to antennas@qth.net last week.

73s and tks for the interest

Lane
Ku7i
San Diego

Reflector <antennas@qth.net>
Sent: Wednesday, September 27, 2000 4:42 PM
Subject: quad user report


> I have built several 2 and 3 element quads and delta loops over the years.
I
> have also built several mono band and multi band yagis. Well this summer
the
> quad bug hit again and I built another one. This time I had to limit the
> boom length to only 16 feet due to the logistics of where the tower was
> located. I elected to go ahead and build 3 elements for 20, 17, and 15
> meters. I will soon add 3 elements on 12 since I have seen some nice
> openings on that band. I rarely ever get on 10 meters so I have not added
> that band yet.
>
> I have NOT modeled this but I am sure that the gain is a little less than
> optimum on 20 since there is only 8 feet spacing between the elements. My
> guess is that there is probably around 8.5 db of gain on that band instead
> of the textbook perfect spacing of 9+. I have all of the driven elements
> paralled together at the feedpoint. I use a Bencher 1:1 current balun
there
> to prevent feedline radiation, although a coaxial choke would probably
work
> just as good.
>
> There is one difference that I have seen over the years.......it is not
that
> the quads are any better or worse than yagis.....but at reduced heights
the
> quad is better. For example, I could only get this one up 35 feet at the
> boom (~ 1/2 wave on 20) but it really works like a champ on all 3 bands. I
> see an average of 6 s  units of front to side rejection and around 3 to 4
s
> units of front to back. I am very happy with this antenna. While in some
> locations the yagi might work just as good as the quad at 35 feet I find
> that at my particular qth the extra capture area of the quad helps it just
a
> little bit at the lower heights.
>
> Please, please do not ask for dimensions. I used the latest Bill Orr quad
> book and the quad book by W4 somebody. The W4 book is GREAT because it is
> loaded with computer models of all kinds of various spacings, elements
> lengths, etc...it was a big help since I wanted to really optimize this
> sucker on the 16 foot boom.
>
> One note is that the W4 author stated that he found reflector lengths of
10%
> longer (I think it was 10, could me less, my memory stinks) was optimum.
> This did not equate with Orr (around 3 to 5%) so I compromised and used 7%
> longer for the reflectors and 7% shorter for the directors.
>
> I am very happy with the results.
>
> Lane
> Ku7i
> San Diego
>


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