Planar UHF tag antenna with bandwidth enhancement

A novel planar loop tag antenna mounted on the plastic pallets for UHF RFID system is proposed. By insetting the U-shaped slot and a pair of rectangular parasitic strips into the proposed loop tag antenna, the resonant mode close to UHF 900 MHz band is excited to enhance the operating bandwidth. The obtained impedance bandwidth across the operating band can reach about 174 MHz (18.8 %) for UHF band. Also, with bidirectional pattern, the measured reading distance is about 2.0 m as the proposed loop tag antenna mounted on the plastic pallets.