[TowerTalk] On the subject of random wire antennas

w5prchuck at gmail.com w5prchuck at gmail.com
Sat Apr 22 18:06:04 EDT 2017

You mean a lot of high angle radiation, don’t you?

Chuck W5PR

Sent from Mail for Windows 10

From: Tom Osborne
Sent: Saturday, April 22, 2017 3:39 PM
To: David Voit
Cc: towertalk at contesting.com
Subject: Re: [TowerTalk] On the subject of random wire antennas

It all depends on what your interests are.

A long vertical has a lot of horizontal takeoff compared to a quarter wave
antenna.  That is why the 40 meter vertical isn't a DX antenna.  73


On Apr 22, 2017 11:28 AM, "David Voit" <dvoit1944 at gmail.com> wrote:

I am going to put up a random wire as a vertical in a tall pine tree and
place a remote tuner at the feed point and fed with coax.  Looking over the
info on random wires, there are various lengths to avoid depending on the
bands you choose to use.  I certainly want 80 meters and I see a variety of
lengths, 72, 85, 106 feet are acceptable.  All of those can be put up in my
trees with my pneumatic launcher and they would be a straight vertical
wire.  If  I want to use 160 meters, it looks like the shortest wire would
be 136 feet and the trees don't go that high.  (I already have a quarter
wave vertical for 160 at 123 feet and it works fine.   Just don't have the
extra 13 feet and don't want to wait for the tree to grow.)

I believe the best answer is to leave the quarter wave wire up and put up
the other antenna.  Of course, I don't want to do that as it requires
another coax run.  I would like to do one random wire for access to all
bands from that antenna, so, my question is would it work to put 136 feet
of wire up and over the top and headed back down but with maybe 3 or 4 feet
separation for the "hook" at the top?  I would guess 5 or 10 feet would be
more or less parallel to the portion going up but looping back down.  Luck
would decide how much is over the tip.  If the over the top hook causes
problems, I would default to the "best answer".

The next part of the question is:  for a vertical wire, assuming I should
not do the 136 foot wire,  is there an advantage for choosing the longer
length among the choices for 80 and above?  Angle of radiation?
Efficiency, (given the feed point impedance  is high, does this relate to
low ground losses)?  I know many radials are important for a quarter wave
vertical but is it for a random wire?

And yes, I understand lightning is a problem.  I'm having fun and gladly
disconnect after use.  This does have the advantage of not needing relief
from the tree swaying in  the wind since it is parallel to the trunk.  My
dipole has to be lowered after I use it just to be sure it does not pull

David Voit

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