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formula needed

To: <>
Subject: formula needed
From: (Pete Smith)
Date: Tue, 23 Jul 1996 03:53:11 -0700
Can anyone provide a general formula for determining the length of an
open-circuited coax stub to provide a given amount of reactance?  I have
found one that works for lengths under 90 degrees (1/4 wavelength), but my
particular problem requires a longer length.  Or is there some automatic
relationship between the lengths less than 90 degrees and those over?  As
you can see I'm no engineer!

The ideal formula would also take losses in the cable into account, and
permit designing for a complex result -- R +/- Jx.

In case anyone wonders ... this is for an 80-meter version of the K3LR
lazy-vee parasitic array -- 25+j93 at each of the three non-driven dipole
feedpoints (as noted in the 8/94 QST article) gives fantastic F/B ratio in
the model, but I can't figure out how to translate this into a length of
RG8X that will get from the feedpoint to the switchbox on the tower.

Thanks all!
73, Pete Smith N4ZR 

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