A T-matched dipole antenna with a dielectric superstrate for UHF RFID tag

This paper describes a high impedance matched dipole antenna, which is comprised of an inductive T-matched loop and a small bent dipole radiator with a slit for UHF RFID tag design. The overall dimension of the tag antenna is 36 mm × 28 mm. The input impedance of the designed tag antenna is 49.2+j787.6 Ω and is conjugately matched to a FEC-MMGen2/MM3BS microchip with an impedance of 49.2-j787.6 Ω at 915 MHz. The T-matched coupling mechanism can excite dual-mode to enhance the impedance bandwidth for solving the narrow bandwidth of the RFID tag. The maximum read range of the prototype with a superstrate can reach approximately 2.4 m, which has been tested for an RFID reader with 4.0 W of EIRP. Good tag sensitivity and orientation radiation patterns were obtained in the desired frequency band.