Brian Kelly wrote:
I'm in the process of stringing two base-fed half wave verticals up in
a big beech tree, they're Dale Parfitt's End Fedz dipoles for 20 & 15M.
I've used the duoband EF-20/40 (since replaced by the triband
EF-10/20/40) for several years for portable QRP operation. The real
advantage of these antennas for field operation is their light weight
plus simple erection by tossing them into a tree :
http://users.vnet.net/btippett/catal..._trail_qrp.htm
Dale W4OP is very knowledgeable and responsive. I would try a direct
e-mail to him via par at parelectronics.com , however his FAQ page on
the End-Fedz FAQ page states:
http://www.parelectronics.com/pdf/FAQ%20End%20Fedz.pdf
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Q: Do the EndFedz require a ground?
A: The simple answer is no. With over 4000 antennas in the field, we
know of one instance where RF was "in the shack." This occurred
with the antenna directly over the operating position. Moving the
antenna solved the problem. If you do ground the antenna at the
matchbox, you will likely see no change in VSWR or resonant frequency.
The only conditions where we were able to measure significant RF on the
outer coaxial shield occurred when:
1. The coaxial length was an odd multiple of ¼ wavelength AND
2. The rig was grounded.
In this instance we measured current -7dB down from the peak antenna
current.
Changing the coaxial feedline length OR removing the ground
significantly reduced the currents.
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Based on the above and my own experience (QRP rig plugged directly into
the coax connector), I doubt you will need a ground. As I said before,
ask Dale. He is extremely responsive and he seems to know what he is
doing (see below).
http://www.parelectronics.com/index.html
73, Bill W4ZV
P.S. Since you want monobanders, you might consider rolling your own.
I made one for 40m but wanted the versatility of Par's duobander for
portable opertion. The designs below do require a counterpoise wire
but are quite easy to build. See multiple links at the bottom of this
page for more info:
http://www.aa5tb.com/efha.html