Low RCS multi-bit coding metasurface modeling and optimization: MoM-GEC method in conjunction with genetic algorithm

Abstract

We propose a new approach to design multi-bit coding metasurfaces (MSs) for broadband terahertz scattering reduction. An anisotropic graphene-based element with multiple reflection phase responses is modeled using the Method of Moments combined with the Generalized Equivalent Circuit’s approach (MoM-GEC). The multi-level reflection phase response is adjusted by tuning the graphene chemical potential of each cell. Based on the coding metamaterials concept, 1-bit MS building blocks are nominated as “0” and “1” elements with opposite phase responses 0◦ and 180◦, respectively. Therefore, the genetic algorithm (GA) is employed to search the optimal reflection phase matrix and determine the best coding metasurface layout. In order to validate our design strategy, 4 × 4, 8 × 8, 16 × 16, 32 × 32, and 64 × 64 arrays (MS) are modeled and show a great agreement with the desired low Radar Cross Section (RCS). In addition, 2-bit and 3-bit coding metasurfaces are then designed using two different sets of reflection phases {0◦, 60◦, 120◦, 180◦} and {0◦, 30◦, 60◦, 90◦, 120◦, 150◦, 180◦, 210◦}, respectively.