宽带高增益环形圆极化微带天线

Two novel single-fed ring circularly polarized microstrip antenna with an enhancing bandwidth are designed to broaden the axial ratio bandwidth of the cut ring patch antenna. Since the lateral slot perturbs the surface current of the ring patch, two equal-amplitude radiation modes with a phase difference of 90° are excited to radiate circular polarization. The measured results show that good circularly polarized characteristics of the annular-ring and the square-ring antennas have been obtained respectively from 3.74 to 3.98 GHz and from 3.80 to 4.04 GHz. The axial ratios (ARs) are less than 3 dB and the voltage standing wave ratios (VSWR) are less than 2. In addition, the antenna peak gains are higher than 10.0 dB for annular-ring and square-ring microstrip antennas over the operating bandwidth.