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[TowerTalk] phasing antennas

To: towertalk@contesting.com
Subject: [TowerTalk] phasing antennas
From: Bill Tippett <btippett@alum.mit.edu>
Date: Tue, 15 Mar 2005 09:23:18 -0500
List-post: <mailto:towertalk@contesting.com>
I wrote:
 >If you look at a model of a stack,
the pattern is fairly insensitive to slight differences in phase.
I recall seeing little difference for ~10 degree phase difference,
which is far more error than you would get by simply cutting
lines to the same physical lengths, even on 6 meters.

         I did a quick check of this using an old (pre-YO7)
Eznec model when I was modeling a stack of my KLM 610's.
This is for a two antenna stack, as you will have on 6m.
I used 1 wavelength spacing:

Phasing Gain (over flat terrain)

In-phase        16.85 dBi (all at 8 degrees TOA)
Bot +10 16.83 dBi
Top +10 16.81 dBi

Assuming Vf of 0.8 for your coax, 10 degrees equates to
5.25" difference in coax length at 50 MHz.  Since you
can probably cut your coax closer than that I wouldn't
bother with tuning it, although I would still check with
the MFJ just to be sure there are no problems.

                                         73,  Bill  W4ZV


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