Can a Smart Phone Generate an LF, HF or UHF RFID Signal Without Having an NFC Chip Inserted in It?

Unfortunately, this is not something that is possible. Low-frequency (LF) and high-frequency (HF) tags have coiled antennas that couple with a coiled antenna in the reader antenna. Cell phones have no coiled antenna with which to couple. Moreover, cell phones operate at a much higher frequency—usually the 800 MHz band.

I spoke to an engineer regarding whether a cell phone could be turned into an ultrahigh-frequency (UHF) RFID reader, since UHF systems operate in the 900 MHz band. Tags could be tuned to the 800 MHz band, the engineer says, but additional hardware and firmware would need to be added to the cell phone in order to turn it into an RFID reader. It makes much more sense, he says, to add an NFC chip or UHF reader chip to add on RFID capabilities, rather than trying to redesign the operation of the phone's antenna.