Why does UHF RFID TAG CHIP NOT use differential ports?

Anybody in work on UHF RFID design?

We've been discussing differential impedance measurement for RFID antennas or tag chips, one question still bothers me, which is below.

As we all know,dipole has differential ports, as the load of antenna,the TAG CHIP usually has single-ended port. Such as NXP/Alien, the tag chips have only one RF port and another GND port. Is there anything wrong or problem when single-ended tag chip connects differential antenna even though conjugate matching is achieved(but how to consider or design the matching between differential source and single ended load?)

I've NOT seen any paper or article on tag chip impedance measurement which is differential till now, but some new tag chip just like Monza4/5,they really have differential RF ports,ie. no GND pad exists. Is there anyother chips have differential RF ports on market?

is this a esay or simple question?