A miniaturized circularly polarized (CP) antenna for ultra-high frequency (UHF) radio-frequency identification (RFID) reader is designed in the present paper. For the aim of miniaturizing antenna, the square radiating patch is opened by four T-shape slots. This can extend the route of surface current, as a result the operating frequency drops and the size reduces. In additional two diagonal corners of the radiation patch are truncated by a square to achieve CP operation. The designed antenna is calculated and optimized by HFSS. The optimized antenna exhibits satisfied performances, and is therefore suitable for UHF RFID reader applications. The designed antenna shows the advantages of small size, simple structure, and low cost.
Dual-Band Dual-Sense Circularly Polarized Stacked Patch Antenna With a Small Frequency Ratio for UHF RFID Reader Applications