Optimization Design of a Wide-Angle Broadband Composite Absorber of Plasma and a Metasurface

This article presents an optimization design method for wide-angle broadband composite absorbers consisting of a plasma and a metasurface. The transmission line (TL) model is employed to present the designed composite absorber, with the minimum reflectivity of the absorber under large angle oblique incidence serving as the optimization objective. A genetic algorithm (GA) is utilized to optimize this composite absorber design. The designed composite absorber combines the absorption capacity of the plasma at low frequencies and the metasurface at high frequencies. Initially, a composite absorber comprising a homogeneous plasma and a metasurface was designed, achieving an attenuation of more than 10 dB for incident electromagnetic waves within the ±45° angle range and in the frequency range of 8-14 GHz. A composite absorber composed of a double Gaussian distribution plasma and a metasurface is subsequently designed, resulting in an attenuation exceeding 10 dB for incident electromagnetic waves within the ±45° angle range and in the frequency range of 6-16 GHz, as well as an attenuation exceeding 60 dB at 12 GHz when vertically incident. A conformal composite absorber consisting of a double-Gaussian distribution plasma and a metasurface is designed; its radar cross section reduction (RCSR) achieves -10 dB in the frequency range of 4-17 GHz compared with that of metal plates. On the basis of these three design examples of composite absorbers, we confirmed the effectiveness of our proposed optimization design method for wide-angle composite absorbers consisting of a plasma and a metasurface. This optimization design method effectively addresses the challenge of designing absorbing structures under complex media coverage, such as plasma.