Topband: Improving Inverted "L"?

herbs@surfvi.com herbs at surfvi.com
Thu Oct 27 20:38:42 EDT 2005


Quoting Jerry Keller - K3BZ <k3bz at arrl.net>:

> Herb... sorry if this is a dumb question, but does that mean that 
> instead of a "tee" I could split
> the horizontal portion of my 160M Inverted-L  into 3 or 4 segments 
> going in different directions
> from center, as long as the total vertical plus horizontal portions 
> equal about 135 feet, and the
> vertical portion is as long as possible? What (if anything) does that 
> do to the feedpoint matching?
>
> Sure Jerry...the more top loading the better.  The wires should all be equal
length if possible.  There is a military version of this design with three
wires against a three wire mirror counterpoise and it is call a "crowsfoot".
More top loading should drive the impedence a bit higher and could cause a bit
of inductive reactance(depending on length) that can be tuned out with a
series cap.  With a 40 foot vertical portion you can also end up with less
length in each horizontal wire.  It all depends on the ground and the number
of radials.... wherein a EZ-NEC software can do a better job at determining
the values acurately.  It also depends on the area you may have available for
the toploading wires.  Even 40-50 feet in all horizontal directions would be
fine while leaving the final match to a L-network or tuner at the feed point.

Good Luck,

Herb Schoenbohm, KV4FZ


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