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Re: [TowerTalk] Help needed with Antenna Model

To: <towertalk@contesting.com>
Subject: Re: [TowerTalk] Help needed with Antenna Model
From: <john@kk9a.com>
Date: Sun, 17 Sep 2017 22:38:07 -0400
List-post: <mailto:towertalk@contesting.com>
I have no experience with Antenna Model (I never even heard of it before
your posts) however with other modeling programs center (or 50% in) works
perfectly when there is a odd number of segments.  Usually you can manually
changed the number of segments. Since this is not working for you, how about
splitting the driven element in the middle (like it actually is) and feeding
it at the segment end?

John KK9A

To:     TowerTalk
Subject:[TowerTalk] Help needed with Antenna Model
From:   Dave Sublette <k4to@arrl.net>
Date:   Sun, 17 Sep 2017 21:03:38 -0400

I am attempting to model the W6NL two element Moxon yagi for 40 meters.  I
have 
a working file. It runs and gives perfect results. The software I am using
is 
the "Antenna Model" program. I selected it because it handles the Moxon 
configuration while some other programs won't.

I attempted to change the file using the diameters and length of tubing I
have 
on hand.  My file will not run properly because I cannot place the source at

element 1, center, as the correct file has.

My elements have 17 segments in the driven and director elements.  The W6NL
has 
19 segments in driven and director.  The "TEE" sections of both files are 
identical and placed at the same points on the driven and director.

Until I can get my file to accept placing source 1 at wire 1, center, I
can't 
begin to tweek my lengths to achieve the desire pattern, etc.

I have proof read until I am crosseyed and see no mistakes in my file. I
have 
faithfully duplicated the placement of the TEES.  The only obvious place to 
find a error is what ever is causing my model to have 17 segments instead of

the 19 in the original file.  I will continue to look there.

It has me stumped..

Anyone care to offer advice?

Thanks & 73,

Dave, K4TO

ps - the program will allow me to place source 1 at wire2, end1.  It will
then 
run, but impedances are all off by a large factor.

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