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Re: Experience with K3TZ patch (construction question)



Hi Cliff,

Thanks for the suggestions.  So, if you don't mind, can I get
a few more details?

By your comment about the need for a solder ball, you mean that
you needed to solder the bump to the top side of the reflector,
right?  What is your reflector made from?  I was thinking of looking
for some aluminum sheet, which would make this difficult.

The distance between the driven element and the reflector, if I
remember correctly, is 3mm.  The bump is about half of that,
so, subtracting the thickness of the reflector itself, there's
still quite a bit of metal sticking into that space around the
center pin.  Doesn't that mess things up?

Also, do you have any suggestions for making the height adjustment,
given I have a lack of 2.4 ghz analysis equipment?  How sensitive
is the resonant frequency to the distance?  I assume we're talking
about making really really really small changes, no?

Thanks,

Greg  KO6TH


>From: Clifford Buttschardt <cbuttsch@slonet.org>
>To: "Greg D." <ko6th_greg@hotmail.com>
>CC: amsat-bb@AMSAT.Org
>Subject: Re: [amsat-bb] Experience with K3TZ patch (construction question)
>Date: Wed, 20 Feb 2002 16:55:43 -0800 (PST)
>
>Greg, I've done just what you have suggested with a few modifications in
>procedure.  First I mounted the type N such that the mounting flanges were
>on the opposite side of the ground plane, thus just the "bump " sticking
>up between the ground plane and the patch.  This was a mistake until I
>realized that I need to put a solder bead between the bump and the ground
>plane nearest the patch.  It was highly successful changing the distance
>between the ground plane and patch simply by heating the center, moving
>the patch experimentally up and down for a new resonant frequency. Also, I
>found that by tilting the patch, I could get better circularity, which is
>an admission that I'd not cut the patch accurately enough but illustrates
>another way the final antenna feed can be optimized!  Cliff K7RR
>
>
>On Wed, 20 Feb 2002, Greg D. wrote:
>
> > Just curious what one would do in building the patch with one
> > of those N connectors with a bump on the back side...  The
> > height of the bump is almost as high as the distance between
> > the reflector and the active element.  I assume I need to put
> > a spacer between the N connector and the back of the reflector
> > in order to move the top of the bump to be flush with the front
> > of the reflector.  So the hole in the reflector would be about
> > a half inch in diameter, and not attached to the top of the bump.
> > The alternative would be a thicker spacer and a hole only big
> > enough for the center pin to pass through.  Probably have the
> > spacer just thick enough so the top of the bump contacts the back
> > of the reflector, but I don't know if that's a reliable connection
> > from an RF perspective.
> >
> > What's the right answer?
> >
> > Greg  KO6TH
> >
> >
> > _________________________________________________________________
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>




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