I couldn´t suffer that an 1.2m dish was unused in my garden.
Therefore, I decided to construct my own QO-100 ground station. Here the feed was analysed with sonnet:
Unfortunately, I was not able to shift the frequency down to 2.4GHz. Sonnet light allows to analyse the antenna, only. Optimization is obviously in the full version possible, only.
Nevertheless, I started to construct the feed, looking forward what will happen.
After everything was soldered the first measurement was taken:
The first measurement after construction:
I have no experience to interprete this S11 trace. My guess ist, that the circular polarisation is not very impressive. So I played around and soldered some copper to the longer edge. At the end everything was removed. Solder remained at the two edges with following result:
I have no clue why the solder will change the trace. I have to admit that all the measurements were done in my shack. Maybe this is the result off all the reflections.
P.S.: In the meantime I know the reason. The solder changes the thickness of the patch and so far the er of the poty-antenna. Changing er results in a significant detuning.