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RE: Circular patch behaves linear

Hi Howard,

Nice work (as usual!)

Based on your pic and the ones on Jerry's site (K5OE) I added
a nylon screw in the center for support. I also added a sheet
of 3mm thick polypropylene foam (dielectric constant = 1) under
the driven element to try to improve the spacing.

By adjusting the nylon screw in the center, thus squeezing the
driven element towards the reflector a little, I was able to get
nearly 20 dB of return loss at 2401 MHz. However, a quick bench
test of the circularity showed it wasn't very circular :(

I do think that using a thicker material would help but I'm
still not convinced about the no-tune part. The issue isn't that
it won't work. I'm sure it would be fine on a BUD, circular or not.
But, on a 2 or 3 footer, you would really like the extra 3 dB.

Cheers and 73,

Tony AA2TX

At 04:36 PM 6/23/03 +0100, Howard Long wrote:

>Hi Tony
>I built a dual band K5OE/K3TZ patch at
>My version is shown at http://www.g6lvb.com/images/dualbandpatch001.jpg
>where I spent a lot of time getting the measurements as accurate as possible
>using vernier calipers etc.
>FWIW I put it on a network analyser a friend of mine has and achieved these
>plots without any tweaking at all:
>http://www.g6lvb.com/images/patch001.gif 13cm patch 0 to 3GHz
>http://www.g6lvb.com/images/patch002.gif 13cm patch 2151 to 2651MHz (2401MHz
>http://www.g6lvb.com/images/patch003.gif 23cm patch 1019 to 1569MHz (1269MHz
>Sadly I did not try them fitted to a dish.
>73 Howard G6LVB
>Sadly I had not tried them
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