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The multisection Franklin antenna for UHF has been widely published on
the web. The first design is by N9ZIA:

http://www.qsl.net/n9zia/wireless/col432/index.html

This antenna used ground plane radials for decoupling

A modification by N1HFX uses a sleeve and ferrite toroids for
decoupling:

www.rason.org/Projects/collant/collant.htm

There is also a design proposed by WA6SVT with a few variations in
which a tubular sleeve is used and the coax elements covered with
cupper tubes:

http://www.repeater-builder.com/ante...struction.html

I would like to build a pair of vertical multielement antennas for
mobile use (when standing still) use to be used in cdma450 cell fringe
zones. 7-9 dB gain should be enough to reach base stations of the
outskirts of cells.

I suppose that a combination of the principles outlined in the
articles by N1HFX and the ones cited around the WA6SVT design should
work. Any feedback would be appreciated.

Q: How come coils are not used to space half-wave elements from each
other? In several wifi designs, single loop coils are used. In some,
coils consist of several turns:

http://mobileaccess.de/wlan/download...0-all-inst.pdf

So, what size should a phasing coil be for 455 MHz?

Regards
Jonas/SM0WJY


Hi Jonas

It isnt made clear that this colinear array of 1/ wave diplies is quite
sensitive to ferquency change and intolerant to construction errors. If
you ask questions like "what size should the phasing coils be", you find
some difficulty in getting a long array to work. I'd advise you to try one
of the designs that doesnt use "phasing coils" and just try whatever is easy
for you to build.
I have (in the 1960s) designed and manufactured antennas using this end
fed concept. The radiation pattern is effected by frequency change. The
beam max will squint up with higher ferquencies and downward with lower
frequencies.

Jerry KD6JDJ