And is it possible to increase that number?
Many passive ultrahigh-frequency (UHF) RFID readers have four or eight ports. It is possible, however, to use multiplexers to increase that number to hundreds of antennas. Special software would be required to manage that many antennas, but essentially, the reader would briefly turn on each antenna in a set sequence, and cycle through them repeatedly. There would be some degradation in the signal, especially as the length of cabling to the antennas increased.
—Mark Roberti, Founder and Editor, RFID Journal