Optimization-Assisted Design of Wide-Band Structured Microwave Absorbers

The obtention of highly absorptive surfaces over a wide frequency band and a wide angular range requires the complex manipulation of both electromagnetic properties and geometrical structure of materials. As a matter of fact, a periodic arrangement of sub-wavelength patterns can greatly improve the performance of an absorber with minimum thickness over a large set of conditions. Yet, this inevitably leads to a significant number of geometrical parameters making the design of absorbers fastidious and time-consuming. This paper presents a fast design methodology for microwave absorbers. An optimizer based on the algorithm Covariance Matrix Adaptation Evolution Strategy (CMA-ES) iterates over the results provided by a simulation code based on the Fourier Modal Method (FMM), in order to reach a targeted absorptivity of 1. To illustrate this fast design methodology, we present the optimization of a 10mm-thick structured microwave absorber made of a magnetodielectric material.