Mechanism and Applications of Electric and Magnetic Modes of Double-layer Metasurface

In this paper, the physical mechanism of double-layer metasurfaces is discussed based on Huygens’ principle. It is demonstrated that double-layer metasurfaces can support both electric and magnetic resonant modes. The electric resonant mode arises from currents on both layers flowing in the same direction, whereas the magnetic resonant mode is a result of currents flowing in the opposite directions. Typically, a magnetic mode exhibits a lower energy level, which corresponds to a lower frequency, in comparison to an electric mode within the same double-layer metasurface. Through adjusting the electric and magnetic modes, we have successfully applied this mechanism to a range of antenna applications, including high-efficiency metalens antenna and broadband reflective antenna.