A Method of Suppressing Higher Order Modes for Improving Radiation Performance of Metasurface Multiport Antennas Using Characteristic Mode Analysis

A method is proposed to suppress the unwanted higher order modes (HOMs) of the metasurfaces in multiport antenna systems for improving the radiation performances using characteristic mode analysis (CMA). The proposed method is to control the modal currents under consideration by loading the unit cells of the metasurface with slots and vias. The positions of loads are determined with the aid of CMA of the metasurface. For proof of concept, the proposed technique is applied to a compact wideband four metasurface antenna (MA) systems operating at 5 GHz Wi-Fi bands. With the suppression of HOMs, the split and tilted radiation patterns of the MAs are significantly improved. The concept is experimentally validated for potential compact multiport antenna applications.