High capacity polarization sensitive chipless RFID tag

A radio frequency identification (RFID) chipless tag that achieves a high code capacity through multiple closed loop printed resonators is presented. By making the resonators polarization dependent, the same frequency band within UWB from 3.1 to 7.6 GHz is re-used, hence doubling the code capacity of the tag. The chipless tag is excited using linearly polarized vertical and horizontal plane waves and the radar cross section versus frequency is analyzed. Using frequency shift encoding enables each of the six resonators to represent more than one bit. Thus, in a small tag dimension of 6 × 3 cm², encoding of 28.4 bits is demonstrated.