Jerry Haigwood, W5JH, reminded me that the low impedance, narrow bandwidth
characteristics of 2-element Yagis, which make them a bit problematical on
wider ham bands, can be overcome for the narrower WARC bands, such as 12
and 17.
So I did some further exploration of these antennas and developed some
models with very nice F-B ratios (>20 dB) and gain that is higher than
that of the standard Driven Element/Reflector 2-el Yagi.
This would not have been anything new or worth noting, but I then began to
dream a bit, first about back-to-back independent beams for 12 and 17 on
an 8' boom. Then I combined the beams, still back to back by using open
sleeve coupling to simplify the feedline to just one for both. Now that
seemed worth noting, so I added an entry on Director/Driven Element Yagis
to the website, including the preliminary design for the one-feed array on
a 7' boom.
Even if you prefer separate feed lines, at about a foot spacing, DE to DE,
the antennas show very little interactions. So with an 8-9' boom, you can
get the same performance--or tailor it to your preferences.
Hope the notions are of interest to someone. and thanks again to Jerry
for the reminders.
-73-
LB, W4RNL
L. B. Cebik, W4RNL /\ /\ * / / / (Off)(423) 974-7215
1434 High Mesa Drive / \/ \/\ ----/\--- (Hm) (423) 938-6335
Knoxville, Tennessee /\ \ \ \ / / || / (FAX)(423) 974-3509
37938-4443 USA / \ \ \ \ || cebik@utk.edu
URL: http://funnelweb.utcc.utk.edu/~cebik/radio.html
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