Design of Miniaturized Fractal RFID Tag Antenna with Forced Impedance Matching

A new optimization based-methodology for miniaturizing RFID tag antenna is introduced. In this paper, the particle swarm optimization (PSO) technique in conjunction with CST Microwave Studio electromagnetic simulator are used to design a miniaturized fractal antenna having perfect impedance matching with the tag chip. The design does not need any additional loading or matching network and hence yields relatively lower cost and smaller antenna size compared with conventional tag antenna systems. A combination of two objective functions related to power reflection coefficient and antenna area are used for optimizing the antenna. The design methodology is applied to a 3rd-order Minkowski fractal nested-slot patch antenna and yields 90% area reduction compared with the reference (non-fractal) counterpart.