I'm working with a PN7462 NFC reader and am seeing a collision error every time I attempt to read from a ISO 14443-A RFID card. Hardware wise, The VNA shows that the filter is turned fairly close to the 13.56MHz, and the output power looks good. I can even see that the card is responding to a REQA command, yet the PN7462 is unable to understand the data. I was able to successfully read the result from the REQA command once, but this was out of 100's of attempts.
I cannot find any documentation that points me towards what causes the collision errors beyond attempts to read more than one card at once (which I'm not trying). I suspect it has something to do with the antenna tuning. I'm a novice when it comes to wireless communication in general, so I really do not have any good reason to believe the tuning is the issue outside of the fact that the communication isn't working. On the other hand, the VNA results look to be in line with what is expected according to the AN11532 application note.
Any suggestions on experiments would be helpful. Thanks for reading