Automated design of dual-passband frequency selective rasorber using multi-layer coding metasurfaces with NAGA-II

A compact dual-passband frequency selective rasorber (FSR) based on multi-layer coding metasurfaces (MCM-FSR) is proposed. The lossy layer and the dual-passband frequency selective surface (FSS) are discretized into binary coding patterns with central and diagonal symmetries. A dedicated coding conversion scheme transforms the binary representations into decimal variables, which, together with other structural parameters, are optimized using the non-dominated sorting genetic algorithm II (NSGA-II) to achieve optimal electromagnetic performance. The optimized MCM-FSR exhibits an insertion loss below 3 dB over the broadband transmission bands of 0-4.9 GHz and 16-20 GHz, while achieving absorptivity exceeding 80%% across 8.28-12.44 GHz, with a maximum value of 99%. Notably, the proposed structure maintains a compact thickness of only 7.3 mm. Furthermore, the excellent agreement between the simulated and measured results validates the proposed design methodology and its potential for practical engineering applications.