Realization of non-uniform metasurface antennas based on the characteristic mode theory

This paper explores the design process of metasurface antennas using characteristic mode analysis (CMA). A simple 3 x 3 circular patch metasurface is used as the basic structure. By analysing its CMA and modify the structure step by step, two single-layer non-uniform metasurface antennas operating in the 5 GHz WLAN band are designed. Three horizontally polarized modes of the antenna are excited to form a linearly polarized antenna with a relative impedance bandwidth of 21.8% (4.93-6.13 GHz). The circularly polarized antenna is achieved by adjusting two orthogonal modes, resulting in a relative impedance bandwidth of 16.7% (5.05-5.97 GHz) and 3 dB axial ratio bandwidth above 500 MHZ.