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Re: Experience with K3TZ patch -> updated webpage




On Monday, February 18, 2002, at 04:06 PM, Mike Murphree wrote:

> On Mon, Feb 18, 2002 at 10:00:32PM +0000, Cliff Buttschardt wrote:
>> Hi all.  I'm not sure that the K3TZ patch feed is linear.  In fact I
>> would think it circular since the corners are cut off.  Looking at the
>> photos of what he used it looks like he use a RHCP design for the
>> G3RUH comparison.  Why build a special patch I don't know!  Cliff K7RR
>
> Look at the spectrum analyzer plots he's posted... There's very
> little difference between the dipole and the patch.  There are
> also plots for a helix which to no surprise is circular.

You can build a patch in linear or circular polarization -- only 
difference between the two is a shunt connection between two points 
about 90 degrees apart (see detailed diagrams of the AO-40 UHF patch 
array) which makes an otherwise linear patch circular.  I forget the 
exact dimensions and formulas, but the location of the feedpoint 
determines the feed impedance, and the 50-ohm feedpoint is generally 
outside the radius of the circular-feed shunt ..

"Many that live deserve death. And some that die deserve
life. Can you give it to them? Then do not be too eager to deal out
death in judgement. Even the very wise cannot see all ends." -- Gandalf

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