Ultra-Wideband Microwave Absorption by Design and Optimization of Metasurface Salisbury Screen

In this paper, we have designed an ultra-wideband electromagnetic (EM) absorber based on the concept of metasurface Salisbury screen (MSS), which features low profile, light weight, simple configuration, and robust angular performance. The metasurface with extremely simple patch pattern is utilized to generate diverse controllable reflection phases, in place of the non-dispersive metallic plate used in conventional absorbers, thus achieving a multi-octave ultra-wideband EM wave absorption. Equivalent circuit model is established to analyze the performance of the MSS elements, and then the genetic algorithm and simulated annealing algorithm are employed to optimize the MSS element geometries and their spatial distribution. The proposed and fabricated MSS, with a polarization-insensitive absorption over 88% from 3.74 to 18.5 GHz verified by experiments, shows a considerable bandwidth improvement compared with the conventional Salisbury screen of same thickness which has 88% absorption band from 4.8 to 11.5 GHz. Furthermore, the MSS can still provide ultra-wideband absorption with high efficiency for large incident angle, for example, higher than 82% for 45° incidence. The proposed concept could provide opportunities for flexibly designing ultra-wideband EM absorbers, exhibiting promising potentials for many practical applications, such as electromagnetic compatibility, stealth technique, and so on.