UHF RFID Tag Applicable to Various Objects

Abstract

This communication proposes a label tag and a radiator for both dielectric and metallic target objects in UHF radio frequency identification (UHF RFID). Good impedance matching is achieved by the use of a cross-shaped loop when it is placed on dielectric objects and the inserted radiator. The radiator is printed on plastic substrate with a finite ground plane. After optimization and fabrication based on a geometrical study, the manufactured tag shows the half-power bandwidth of 65 MHz (7.1%) and 17 MHz (1.9%), in free space and on the underlying radiator, respectively. A reading range over 6.2 m with a deviation of 5.1 m (6.2 m-11.3 m) is confirmed on various target objects under the condition of 36 dBm EIRP at 912 MHz in UHF RFID band.