Circularly polarized patch antenna using UC-PBG structure for RFID readers

摘要

A circularly polarized patch antenna using an Uniplanar Compact Photonic Band Gap (UC-PBG) structure for RFID readers is presented. UC-PBG structure is successfully used to reduce surface-waves in order to improve the directivity of the microstrip patch antenna. This antenna is fabricated on a 1.2λ × 1.2λ × 0.012λ FR-4 substrate (permittivity of 4.4 and tan δ=0.02) for the European UHF RFID band going from 0.865 to 0.868 GHz. The −10dB impedance matching bandwidth of the antenna is 10.5% while the −3dB beamwidth is around 53° at 0.866 GHz in the x-z plane. Both experimental and theorical results of the antenna are presented and discussed.