Dear all,
I'm doing some test on the ST25RU3993-HPEV development board, in particular I'm testing the tuning algoritm by using the ST25RU3993 Reader Suite software, both in the last version.
Let me say first that I tested the board with several antenna and I checked them with a VNA and I'm pretty sure that S11 was below -10dB in the 868MHz bandwidth.
As you can see from attched screen the tuning results are not excellent, but what is more strange is that I obtain completely different tuning efficiency If I use different RF path. I tried to change external/internal amplifer path for the same port and by using the same amplifer I changed the port. I wouldn't expect this variation and I need to understand what is caused by to avoid problem and guarantee good distance performance in my future design, since it is a critical parameter.
If anyone has an idea...
Thanks in advance
Niccolò
