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 36degrees 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 70degrees 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. (C) 2003 Wiley Periodicals, Inc.