I ordered the OM5569/NT322ER NTAG I2C plus Explorer Kit and everything works fine with the PCB antenna, but the class 6 flex antenna does not work. Neither with the card reader included in the kit, nor with any mobile phone I tried (4 to 5 different ones).
I unsoldered the IC from the class 6 flex antenna and put it on the PCB antenna and there it works. Then I put the working IC from the PCB antenna on the Flex antenna and there it does not work. I also changed the 18pF capacitor on the flex antenna but I cannot get it to work.
I also did not find any problems like broken traces on the board (I2C communication to the IC works fine). No broken antenna trace.
I assume an antenna from the kit should work with the card-reader from the kit. Or are the reader and mobile phones not compatible to class 6 antennas? Am I doing something wrong?