Cell-Based Domain Decomposition for Metasurface Antennas Design

Metasurface design methods typically follow a two-stage approach based on the (surface) Impedance Boundary Condition (IBC) approximation of the macroscopic behaviour of the metasurface. In the first step, the surface impedance profile is optimized to meet the specifications; then, unit-cells are designed to reproduce the impedance profile. Usually, the metasurface geometry is considered continuous and the (equivalent) current can flow everywhere on the surface. In this contribution, we investigate on the impact of the discretization of the optimization domain, and its decomposition to conform to the actual size of the unit-cells in the context of a deterministic current-based optimization method. It is shown that information on the unit-cell size can guarantee better agreement between the resulting IBC and the actual realization with physical unit-cells. Also, optimization convergence is notably faster.