Those interested in Extended double Zepp antennas may or may not have seen
the 2-meter version using "delay" lines by Rick Littlefield, K1BQT, in the
Summer, 97 Communications Quarterly.
Interestingly, although called delay lines, the technique is essentially a
laid-over shorted inductive stub replacing the split inductor or pair of
shorted stubs one might hang from the feedpoint to remove the capacitive
reactance from the feed Z. One line of the transmission line does double
duty in its stub function and in being part of the antenna line.
The technique can be extended to other stub impedances to also effect a
transformation of the feed resistive component down to 50 ohms. A 300
ohms line will do this with the right length, which is not the same as
that needed for a simple stub function.
I have put some notes on the subject at my web site under the title
"Feeding the EDZ," in case anyone is interested. The technique should
work at either HF or VHF.
Incidentally, I have been trying to track down the problem of the 3rd
graphic in the HB9CV notes--it plays locally but is scrunched into less
than 1/8" of screen space when I access the site in normal mode. It is
the SWR curve of the higher gain 3 element Yagi, so you will have to use
your imagination until I figure out what is happening or not happening, as
the case may be.
Anyone who missed the Huntsville, AL, hamfest missed an excellent show and
a chance a. to see moon rocks and b. to stare the SR-71 in the face, nose
to nose. My thanks to N4MN and his cohorts for a really fine weekend.
-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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