Circularly polarized antenna with U-shaped strip for RFID reader operating at 902–928 MHz

A circularly polarized patch antenna is proposed to operate at 902-928 MHz for Radio Frequency Identification (RFID) reader applications. The antenna is composed of a U-shaped strip and a square patch with truncated corners. By means of the U-shaped strip feed technique, the VSWR of the patch antenna is less than 1.2. In addition, the structure of the proposed antenna is simple and low-cost. Simulation results show that the proposed antenna has an impedance bandwidth (1.2:1 VSWR) of about 123 MHz (865-988 MHz), a 3dB axial ratio bandwidth of about 28 MHz (902-930 MHz), and a gain level of about 8.8 dBi.