Millimeter-Wave Circularly Polarized Staircase Curl Antenna Array with 50% Axial Ratio Bandwidth

A wideband circularly polarized (CP) staircase curl antenna array with 50% Axial Ratio (AR) bandwidth is proposed for 5G millimeter-wave (mm-wave) applications. Firstly, the principle of the staircase curl element is investigated. It achieves 57.9^% 3-dB axial ratio (AR) bandwidth and wider than 71.8% impedance bandwidth. Then, a full-corporate microstrip feeding network is designed to construct the wideband CP antenna array. Finally, an 8×8 wideband planar antenna array is fabricated. Measurement results shows that the AR bandwidth is wider than 53.6%, the impedance bandwidth covers from 22.6 GHz to 45 GHz (66.3%), whereas the peak gain is 18.7 dBic. The proposed antenna array demonstrates a promising candidate for 5G mm-wave wireless systems.