My company is using MFRC522 to read the ID of Ultralight tags on a custom PCB for a consumer application.
However I have found a significant difference in range between different tags. MiFARE Ultralight NTAG213 only have ~2cm of range whilst an older MiFARE Ultralight tag (not certain of the type but suspect NTAG203) has ~5cm of range.
This was confirmed using a 'Arduino compatible' development board.
Is it to be expected for the NTAG213 to have a lower range? How could the range be improved? (we have already tuned the antenna to be resonant and 500ohms)