Miniaturized Circularly Polarized Microstrip RFID Antenna Using Fractal Metamaterial

摘要

A novel miniaturized circularly polarized (CP) microstrip antenna that can handle UHF band (920-925 MHz, corresponding to the assigned band for RFID in China) has been designed, fabricated, and measured in this paper. The miniaturization of antenna is achieved by a special cross-shaped fractal metamaterial structure that is inserted between the patch and ground plane. The measured results show that the antenna possesses an impedance bandwidth of 8.7% with VSWR ≤ 1.5:1 and 3-dB axial bandwidth of 3.8%. Furthermore, the proposed antenna has 10.2% size reduction compared with traditional patch antenna. The tested results are in good agreement with that of the simulations.