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Re: Topband: Using wires from large trees as verticals?

To: "Jerry Keller (K3BZ)" <k3bz@arrl.net>,"Jim Brown" <jim@audiosystemsgroup.com>, <topband@contesting.com>
Subject: Re: Topband: Using wires from large trees as verticals?
From: "Herbert Schoenbohm" <herbs@vitelcom.net>
Date: Wed, 14 Nov 2007 15:33:38 -0400
List-post: <mailto:topband@contesting.com>
> Will this cage idea work for the vertical portion of an inverted ell if
the
> horizontal portion is a single wire? Or would the use of a single wire for
> the horizontal potion negate the bandwidth-improvement of the cage?
> 73, Jerry K3BZ


It is my understanding that it would seem to depend on the amount of top
loading induced in the horizontal length of the L.  The best compromise, if
you are stringing an inverted L from trees of approximately similar heights
would be to drop the cage from the center of the "T" as much in the clear as
possible.  This may (1) allow for a better placement of radials (2)  by
cancelation effect avoid the high angle wasted radiation from the flat top,
(3) require less real estate for the flat top length, (4) and move the high
current lobe up the vertical radiator (depending on flat top length) and (5)
farther away from the very trees we are concerned about.

To cage or not to cage is not as much as an issue in this case except that
cage feeds (of steel towers and wire "T" antennas) tend to increase the B/W
so maybe one tuner setting can cover a greater portion of Topband with a
VSWR under 2 to1.

Herb Schoenbohm, KV4FZ

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