A Broadband Dual-Polarized Antenna With Pattern Reconfigurability for Multi-Tag Detection in Chipless RFID

Blind source separation (BSS) technology is employed to address anti-collision detection of frequency-coded chipless radio frequency identification (RFID) tags, where multiple mixed backscattering signals are required to be separated. To enable multi-tag detection in chipless RFID, the antenna is required to feature a broad impedance bandwidth, dual polarizations, wide half-power beamwidths (HPBWs), and, most importantly, pattern reconfigurability controlled electrically. To achieve these design goals simultaneously, a pattern reconfigurable antenna with 20 diverse patterns and 100 detection states is proposed over 2.06–6.37 GHz (120%). The proposed antenna is constructed as an antipodal Vivaldi topology, where various patterns are controlled by the switching of diodes. To validate its capability, the proposed antenna is applied to multi-tag detections for 5-bit chipless RFID over 2.0–5.0 GHz. When four chipless tags separated by only 6 mm are present, the proposed antenna can generate various beams to accommodate the number of tags, collecting mixed backscattering signals for the processing using independent component analysis (ICAs). Due to various samples collected with diversity, the mixed signals can be separated and identified into individual IDs, demonstrating the potential of the proposed antenna for multi-tag detection in chipless RFID applications.