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Re: [TowerTalk] 4 Square phase line length question

To: "Jim Lux" <>, "Dan Levin" <>,<>
Subject: Re: [TowerTalk] 4 Square phase line length question
From: "Tom Rauch" <>
Reply-to: Tom Rauch <>
Date: Sun, 9 May 2004 12:30:54 -0400
List-post: <>
> > The hybrid does NOT provide equal voltages at the output
> > ports, and it requires matched loads for predicted
> However, it's presumed that one could adjust fewer
components in the hybrid
> to compensate for the band change than fiddling with each

A four square has two elements on the diagonal fed in-phase
to form a virtual single center element. It is really like a
three-element in line array with a very wide center element.

Let's assume we tweak components to obtain a 90-degree shift
(which is not optimum anyway) and correct VOLTAGES at the
output port compared to the common point. The hybrid only
controls the current and phase relationship between two out
of the three (virtual) elements. Tweaking the ratio and
phase between two elements and ignoring the other isn't
likely worth the effort. The array requires equal currents
in each element ( the fact there are two center elements is
what gives it what is effectively a 1:2:1 current ratio),
and it requires a phase shift larger than 90-degrees for
optimum pattern.

How would we handle the remaining port in reference to the
other elements?  Add another network? How would we measure
and adjust that mess?

I think it is better to leave it all alone than to open a
can of worms that could likely make things worse!! Hybrids
work OK as is. If someone wants an exceptional array, they
wouldn't use 90/180 degree shift, a dump resistor, and they
wouldn't use a system that forces equal power.
A person that fussy would not be using a hybrid.

73 Tom


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