Circularly Polarized V-Shaped Patch Antenna for RFID Application

A circularly polarized (CP) V-shaped patch antenna is proposed. Different from normal patch antennas, the suggested antenna employs a 3-dimentional V-shaped patch as the radiator. Two wings of the V-shaped patch gradually change antenna height and provide the impedance taper, therefore increases the bandwidth. The bottom of the "V" avoid large inductive reactance introduced by long feed probes. And a metal screw shorted to the ground has been added to significantly improve the impedance matching and CP performance. Good agreement has been observed between simulation and measurement. Measured results show that this antenna has an impedance bandwidth (|S
₁₁
| <; -10 dB) of 22 %, and a 3 dB AR bandwidth of 4.4 %, gain is around 8 dBi with a 915 MHz center frequency. Overall, the proposed antenna is very suitable for RFID applications.