Multiobjective Optimization of Coding Metamaterial for Low-Profile and Broadband Microwave Absorber

The design of a multilayer coding metamaterial absorber (MCMMA) is a multiobjective problem for maximizing the electromagnetic absorption bandwidth (EAB) and minimizing the total thickness by selecting the optimum variables such as the configuration parameters and the resistive film distribution of the metamaterial unit cell. Empirical methods and parameter sweeping have local search problems and converge slowly. In this letter, a multi-objective optimization method is proposed for a low-profile and broadband MCMMA design. A topological encoding strategy is presented for the resistive film distribution where a 10x10-pixel array is divided into five parts with the real-valued representation. The non-dominated sorting genetic algorithm (NSGA-II) is employed to globally search for the combination of the resistive film distribution, geometrical, and material parameters. With an EAB of 142.68%, the designedMCMMArealizes microwave absorption bandwidth covering 7.24-43.28 GHz with only 4.05 mm, which is further fabricated and measured. The experimental result agrees well with the simulation result. This letter provides a valuable method for designing a low-profile and broadband MCMMA, thereby paving the way for coding metamaterials.