A Low-profile Circularly Polarized Antenna with Double U-shaped Arms for UHF RFID Applications

抄録

The proposed antenna structure consists of double U-shaped strip structures and a capacitive feeding line to generate circular polarization. From the results, the antenna has the |S11| less than -10 dB and axial ratio less than 3 dB that can cover UHF RFID band in Thailand (920 MHz to 925 MHz). The bidirectional beam is obtained with the maximum gain paralleled to the ground plane of 2.8 dBi at the 920 MHz. The proposed antenna is low-profile, circularly polarized, and the main beam direction is parallel to the ground plane.