A SMALL RFID TAG ANTENNA USING PROXIMITY-COUPLING TO IDENTIFY METALLIC OBJECTS

摘要

This article presents the design of a small- and low-profile radio frequency identification tag antenna in the UHF band that can be stuck to metallic objects. The designed tag antenna, which uses a ceramic material as an antenna substrate, consists of a radiating patch and microstrip lines for a proximity-coupled feeding structure. Impedance matching can be simply obtained between the antenna and tag chip without any matching network using the antenna structure. The return-loss bandwidth for S{sub}11 ＜ 10 dB and radiation efficiency are about 9.5 MHz and 40% at 911 MHz, respectively. The read range is approximately from 3 to 3.5 m when the tag antenna is mounted on a metallic surface.