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23cm attempts on Ao40



Hi AMSATs,

Yesterday I tried to be qrv on Ao40 via 23cm uplink, but unfortunatly it was 
like impossible.
My setup was a self-made 2m--> 23cm converter with 20W pep, into 23cm patch.
The connection between the converter and patch was only 1m aircell 7 coax, 
to reduce losses, but still no signals on the downlink to be heared.

After some qso's via 70cm with other amateurs I find out that my patch must 
be to little gain for the Ao40 satellite, so I decided to try some other 
more gain antenna's. I decided to make some 23el. loop-yagi from old copper 
water-pipes and thick copper wire. On internet I found some data, but all 
with copper strips. Still made the loop-yagi with the copper wire, and 
finally tested it.

The results were great :-) Reflection is more than 20dB, so SWR abt. 1:1.2
I was very suprised because it was not made to be perfect, and it will never 
win any beauty price haha.

After all I compaired my loop-yagi with the path I have. I At abt. 50m 
distance I set up my converter, and let it TX some 1W into a dummy. Via the 
patch I could recieve a very weak signal, but via the 23el. loop-yagi I have 
14dB more !!!!! With 3dB extra gain, because the patch is circulair, this 
would mean that the real difference is 11dB. When a patch antenna has abt. 
8dB gain, than my loop-yagi would have 19dB gain, but I don't believe this 
is true.
In "ROTHAMMEL" is written that a 27el. loop yagi can have 17dB. So where I 
get the 19dB from ?????

On the other hand my patch can be bad. But it is made from copper and with 
the sizes published in AMSAT-DL. This antenna is also measured to best VSWR, 
some gain reduction I can not disagree, but not that much...

Then I like to say some more about 13cm patches from experience. Just by 
accident I find out that my 13cm patch I use for my portbale station was not 
LHCP but RHCP. With this With this RHCP patch and my foldable dish I have 
been working Ao40 without problems, for many times !!!
Yesterday I tested my new made LCHP antenna and I noticed only little 
improvement.

I don't know if radio waves in Venlo city are not sensitive for 
polarisation, but somehow I could work Ao40 without problems with an 
opposite polarisation patch. (It was even better then my metal-can + dish in 
my mast !!!)

I don't believe in miracles, but I guess this is one...
Or are patches not that circulair as we believe ??

73 de PE1RAH, William
---

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