Optimal Design of a RFID Tag Antenna Based on Plane-Wave Incidence

In order to increase the detection range and radar cross section (RCS), the patch shape of a UHF RFID tag antenna is optimized using continuum design sensitivity analysis. To maximize RCS and reflect the practical RFID tag operating condition, the design goal is set considering not only the matching characteristics of the antenna but also the induced voltage at the RFID chip terminal when the plane-wave is incident upon the antenna. The complex impedance of the RFID chip is taken into account by defining a lumped port at the chip location. The design results show that the induced voltage at the chip has increased more than 32% after the optimization.