An EM‐coupled dual‐polarized microstrip patch antenna for RFID applications

This paper presents the design and development of a compact dual linearly polarized aperture‐coupled microstrip patch antenna array system for radio frequency identifications (RFID) applications. Two different antenna designs, Antenna‐1 and Antenna‐2, for RFID tag and reader applications are presented at the C and S bands, respectively. The antennas use two symmetric coupling apertures to excite two orthogonal modes for dual‐polarization operation. High isolation of the order of −35 dB is obtained by proper selection of the shape and positions of the coupling aperture. The prototype antenna yields a 14.6‐dBi peak gain, a 36° 3‐dB beamwidth (HPBW), a 30‐dB cross‐polarization level, and isolation better than 38 dB between the two orthogonal polarizations (Tx and Rx) at the S band, and a 7.7‐dBi peak gain, a 70° 3‐dB beamwidth (HPBW), a 24‐dB cross‐polarization level, and isolation better than 38 dB between the orthogonal polarization at the C‐band, respectively. The antenna yields a 10‐m identification‐read range in the field trial. The findings are very promising for RFID applications.