60-GHz Substrate-Integrated-Waveguide-Fed Patch Antenna Array With Quadri-Polarization

This communication presents new design of a quadri-polarization-agile aperture-coupled patch antenna array for 60-GHz applications. Four polarization states, namely, vertical linear polarization (VLP), horizontal linear polarization (HLP), left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP) can be flexibly reconfigured by dynamically switching the excitation of the corresponding port. More importantly, as the LP and CP radiations are achieved by using differential feeding and sequential-rotation (SR) feeding, respectively, the array exhibits wide impedance and axial ratio (AR) bandwidths, high polarization purity as well as symmetrical pattern with the main beam fixed at boresight. The -10-dB impedance bandwidths are better than 11.6 % (57-64 GHz) for the four polarization states. The measured AR bandwidths are from 58 to more than 64-GHz for both LHCP and RHCP. The good radiation performance together with the quadri-polarization-agile capability of this new array, as demonstrated in the communication, underlines its suitability for the future 5G communication systems, especially in a multi-path propagation environment.