Short-ended coplanar strip antenna for UHF RFID tags

Recently, more and more research activities have been focused on the radio frequency identification (RFID) systems due to their applications in the supply chain management and security identifications. Among them, the design of small tag antennas with high inductive impedances is one of the most challenging tasks. To have a better power transfer between the tag antenna and the chip, the input impedance of the antenna must be conjugate matched to the chip impedance, which, in most cases, is highly capacitive. In this paper, a short-ended coplanar strip (CPS) antenna with very small size is proposed to be highly inductive. A prototype of this antenna designed at UHF band and conjugate matched to the chip impedance Zc = 16-j350 Omega of the Philips EPC 1.19 ASIC is implemented and tested. Details of the antenna design and simulation and experimental results are presented and discussed.