Design of a loop antenna with stubs for RFID tag

In this paper, a loop antenna with stubs was investigated for UHF RFID tag application. For reactive impedance matching of a loop, open and short stubs were used. Two types of stubs were designed symmetrically with respect to the feed point of a loop. The impedance of proposed tag antenna can be easily matched to that of tag IC by optimizing the dimensions of stubs. The antenna was fabricated by etching on a thin flexible PCB (Material: Polyimide, epsiv_r=3.4, thickness=1mil). Furthermore, the proposed tag antenna could be designed on thin film or paper using inkjet printing method for simple, fast and low cost fabrication.