[TowerTalk] Hex Beam

[L. B. Cebik]

Eric,

Your models are most interesting and very likely quite accurate for a
monoband hexbeam configuration--facing Ws.  Other beams having
similarities of geometry tend to coincide in relevant properties with your
modeled performance.  For example, the folded X-beam, which also has the
two element in close proximity in the feedpoint region, achieves its
maximum 180-degree front-to-back ratio with a feed point impedance in the
mid-20s.  The Moxon rectangle, which also has the element ends carefully
spaced for coupling that establishes performance characteristics, has a
much wider SWR bandwidth than it does a gain and F-B bandwidth.  This
characteristic seems common to many antennas with closed or nearly closed
geometries, including 2-element quads, with the SWR increasing more
rapidly below the design frequency than above it.  The low SWR above
design frequency can create an illusion of proper operation, although the
gain continues the decrease, as does the SWR.  In every way, your model is
consistent with one I did before the original design appeared in
Communications Quarterly some years back.  However, I did not dredge my
old model out of the files, since I did not know what futher development
might have occurred.  However, your model rang every bell related to the
old one and to my studies of various closed-geometry antenna types.  I
believe you have given the design type a very fair appraisal.

-73-

LB, W4RNL

L. B. Cebik, W4RNL         /\  /\     *   /  /    /    Tel: (865) 938-6335
1434 High Mesa Drive      /  \/  \/\     ----/\---    http://www.cebik.com
Knoxville, Tennessee     /\   \   \ \   /  / || /    e-mail: cebik@utk.edu
37938-4443     USA      /  \   \   \ \       ||     e-mail: w4rnl@arrl.org





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