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Re: [TowerTalk] On the phase shift in current between ends of a coil

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Subject: Re: [TowerTalk] On the phase shift in current between ends of a coil
From: "Mark Beckwith" <>
Date: Sun, 23 Nov 2003 08:01:19 -0600
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Phase Shift?  This thread would have made me cross-eyed if I had studied it
so I have not been following it.  Nevertheless this excerpt caught my eye:

>A lumped model serves as a decent design
>tool to determine a starting point, which
>will have to be further iterated empirically.

I like to use AO/YO to design yagis, but I needed my 40M antennas to have
elements no longer than 60 feet because of the guy wires above where they're
mounted.  So I knew I had to load up the elements a little bit.  As much
faith as I have in AO/YO for plain-ol' monobanders, my confidence goes out
the window when you start loading them up.

So I used the empirical approach to build these 40s.  I modeled a full-sized
antenna which gave me the positions of the elements on the booms, worked
backwards to determine the resonant frequencies of the elements, then by
experimentation adjusted each element until it was resonant at the right
frequency, then put the antennas together and put them up.

They work well.  Anyway, 2 cents worth of practical experience from the

Mark, N5OT


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