Integral Equation Method with Customized Entire Domain Basis Functions for the Efficient Analysis of Metasurfaces Consisting of Arbitrarily Shaped Elements

Metasurfaces (MTSs) represent a class of artificial materials composed of subwavelength structures that can be engineered to manipulate electromagnetic waves in a highly controlled and tailored manner. At microwaves, MTSs are typically implemented as dense patterns of electrically small patches printed on a dielectric slab, and modulation is achieved by varying the size and/or the shape of the patches. Thanks to the subwavelength dimensions of the patches, the macroscopic behaviour of a MTS can be conveniently described in terms of homogenized quantities, like equivalent impedance or refractive index, which significantly simplifies the design. Nevertheless, a rigorous full wave analysis of the real structure is always needed to fully assess the performances, especially in terms of frequency behaviour and tolerance sensitivity. However, the model of MTS-based devices is inherently multiscale, which implies high computational complexity, possibly accompanied by ill conditioning.