A High Gain Circularly Polarized Passive RFID Tag on a Metallic Reflector for UHF Band Applications

A passive radio frequency identification (RFID) tag using a metallic reflector is proposed to covering UHF band. The antenna consists of a metallic square loop, fed by two strips using a T-match structure in order to ensure matching in impedance between the chip and the proposed antenna. The distance between reflector and antenna is set to a quarter wavelength to achieving a maximum gain. The proposed design shows an impedance bandwidth (IBW) ranges from 907 to 932 MHz (25 MHz). Also, a long reading range up to 22.56 meters is obtained at 915 MHz. Moreover, the proposed geometry shows a broadside circularly polarized (CP) radiation with a high gain of 7.72 dBi. The proposed design is suitable for high-gain, CP radiation RFID applications.