Designing metasurface through surface impedance mapping and equivalent circuit model

The recently developed concept of two dimensional metamaterial — the metasurface, provides more convenient method to manipulate electromagnetic wave in a designable way within subwavelength distance. However, most of the metasurface designs rely on the meta-atom's properties to achieve certain EM wave control. In this presentation, we propose the top-down design method of metasurface through the surface impedance or admittance mapping targeting certain wave transmission functionality. For the meta-atom design we show the use of equivalent circuit model in the design procedure which effectively eases the choice of meta-atom that provides the required surface impedance. As an example, we demonstrate the design of an active Huygens' planar metalens that could achieve dynamic and arbitrary focusing of electromagnetic wave in real-time.