[TowerTalk] Fixed Quads

[J. Parise]

I built a similar quad arrangement for last years CQWW CW contest and it
worked extremely well.  If you feed the loops at the bottom corner of the
diamond, the weight of the coax helps pull the antenna into shape.  I built
a triband array with three elements per band, and used element spacing right
out of the ARRL antenna book.  You need to consider lateral supports that
you can pitch a line over to hold out the sides of  the loops.  I used a
piece of 1" diameter PVC about 14" long and attached thin nylon line to each
bands side corner and to the PVC, i.e, each bands director on one side of
the loop to one piece of PVC, etc.  Some line attached to the center of the
PVC was tossed over an adjacent tree branch and pulled to "shape" the quad
loop.  I didn't "nest" the loops, but seperated each band's respective
elements by 3 inches on the catenary.

You will have a lot of wire, rope and line to manage, but the antenna should
play pretty well.  Mine stayed up for about a year before high winds and
falling tree branches took their toll.

GL & 73

Jim W1UK

----- Original Message -----
From: <KI7WX@aol.com>
To: <towertalk@contesting.com>
Sent: Saturday, January 29, 2000 10:11 AM
Subject: [TowerTalk] Fixed Quads


>
> For folks interested in wire antennas and using natural supports, I could
use
> a bit of advice.
>
> In preparation for the upcoming contest events I'm looking at erecting
some
> fixed quad loop "beams".  The loops will be hung from a catenary line
running
> (length wise) NE/SW -> e.g. Europe.  I have about 50 feet of length to
play
> with and the height measures out at 85 feet above ground.  That's pretty
> spiffy as it'll place the center of 20M diamond shaped loops at around 1
> wavelength and 40M about 1/2 wavelength which should be decent for both
> bands.  It will get higher with time as the trees grow .... ..
>
> With that setting, I want to suspend loops for both 40 and 20M from this
> line.  Looking at a driven element and reflector with ~20' spacing for 40M
> and probably 4L on 20M using 10 feet between elements (30' total).  Two
> questions for the group:
>
> (1) Does shape of the loop matter much?  From my reading it appears that
> cubes (diamonds) are credited with very slightly more gain than
equilateral
> triangles.  I'll probably do the pragmatic thing and use what ever shape
is
> easiest, but curious what experience teaches here. It probably doesn't
matter
> except on paper.
>
> (2) For rotatable quads it's obviously possible to build multiband arrays
by
> nesting the loops for higher bands within the loops for the lower bands.
> It's not immediately obvious to me why interaction is not a problem, but I
> accept the results.  For my situation, erecting "nested" elements will not
be
> too practical and would likely result in a twisted mass of wire and much
> frustration.
>
> Taking a page from the yagi book, I have pondered "interlacing" the
elements
> to take better advantage of the available catenary length.  For example,
the
> 40M outer elements could surround the 20M elements to give a larger
spacing
> on 40. Alternatively I could add a couple 10M loops inside of the 40M
loops.
> Stuff like that.  Has anyone played with this type of arrangement that can
> offer practical advice?
>
> Cheers,
>
> Mark
> KI7WX/4
>
>
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