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[Towertalk] More on tree antenna mounts

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Subject: [Towertalk] More on tree antenna mounts
From: (W0UN--John Brosnahan)
Date: Sat, 07 Sep 2002 12:25:16 -0500
Peter--yes this is a compromise--but as long as the
cross pipe is significantly shorter than the driven
element and the spacing is on the order of a few feet
a meter or so (and the tree-to-tree support is a non-conductive
rope--or at least non-resonant and separated by a couple
of meters) it will probably work.  And may make operation
possible where otherwise it might not be.

I have done a lot of modeling of antennas--typically
looking at short conductors in the plane of the elements
to add side-guys to a boom.  And as long as these
supports are far from resonance their effect on tuning
is due to capacitive coupling to the nearby element and a
spacing of a meter or so drops this effect down to a very

BTW   I am not supporting or defending the idea--only trying
to demonstrate that you don't have to turn the rotator upside
down for this to work.

John   W0UN

At 05:03 PM 9/7/02 +0000, Peter Sundberg wrote:

>Making the cross pipe long will indeed reduce rotor instability but also
>degrade the beam quite a lot. The same will happen if the cable is made of
>conducting material, especially when the elements are parallell to the
>cable or the cross pipe.
>I've seen better ideas...
>73/Peter SM2CEW

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