Re: Backpackable Antennas

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From: N5EM@aol.com
Date: Tue Jun 06 1995 - 17:11:46 EDT


Michael,

Depends on what you have in mind. For the simplest, lightest antenna, I
prefer a 40 meter dipole, fed with a piece of RG-174U. If fed to a matched
antenna, the loss is nominal and you probably won't want more than 30 feet of
it anyway. The dipole will give you flexibility. Hang it up as a flat top,
inverted vee or sloper, depending on the trees and what you are trying to
work. You can put this antenna into a zip-lock sandwitch baggie after
carefully coiling it up. Normally, I make an effort to locate the antenna in
such a way that the feedpoint is directly above the tent to reduce the
feedline run (since its about 30 feet and hard to stretch). By using this
method, I can live with the short line. Need something about the size of a
golf/tennis ball and some of the high-tech 3/32" dacron, no-stretch, no-rot
cord for getting it up.

Some folks have had sucess with verticals, but I do not want to have to carry
a tuner. No tuner means less weight, less loss, less time wasted trying to
get it running.

Now, if you want to do more in the way of experimenting, you can get more
complicated.

I have considered carrying a delta loop for 40 when weight is not such a
consideration. Needs taller trees, though :-)

Obviously, the available supports are a constraint. I remember Wes Hayward
discussing camping above the tree line and using an ice axe with a
telescoping mast lashed to it.

Also, the telescoping aluminum hiking stick is interesting, although heavy.
 (Several 5-6' sections of AL tubing, starting about 1.25" diameter and
working smaller, using about 4 or 5 sections). Telescope out, with hose
clamps when using as mast. Cap with rubber cane tips when collapsed as a
hiking stick.

Another idea from the QRP Quarterly a couple of years ago was a wooden hiking
stick, ala closet pole, wrapped with a helical winding of wire, fed at one
end with a tuner against a counterpoise. The writer (sorry, I have forgetten
without looking it up at the shack) suggested in a letter to me that one
might use a sitka spruce closed pole, split lengthwise, hollowed out with a
router, glued back together, then wrapped with wire to make a very strong,
lightweight antenna section. Take a piece of water pipe insulation (gray
open cell foam stuff that is split to wrap around your pipes) and use for a
hand support/cusion.

Anyway, there are some of the ideas. Depends on whether you want to (have
to) travel very light or can take more stuff with you.

Let us know what you do and how you like it.

72
Ed Manuel, N5EM
n5em@aol.com


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