Al2O3 based ceramic with polarization controlled meta-structure for high-temperature broadband backward scattering manipulation

In this letter, an ultra-thin Al2O3 based ceramic with meta-structure was designed for high-temperature broadband electromagnetic backward scattering manipulation for Ku band. Distinct from absorptive frequency selective surface with high loss tangent ceramics, the reflection manipulation arose from the out of phase cancellation and polarization conversion of the reflected fields from the meta-structure. To accomplish backward scattering, we utilized Ag and a low loss tangent ceramic with stable permittivity to design the conversion unit, then arranging the units in chessboard metasurface with 0/1 form. Significantly, genetic algorithm (GA) was introduced to optimize both converter and metasurface to obtain broadband performance. As a result, the 1 mm thick metasurface achieved the high-effective beam splitting and RCS reduction over Ku band in the simulation, and the measured result was quite consistent with the simulation that the reflection was attained below −10dB from 11.9 GHz to 18 GHz in a wide temperature range of room temperature to 600 °C. Moreover, the microstructure observation after high temperature treatment reveals that the stable temperature-resistant of the Al2O3 based metasurface. What's more, this achievement indicates the ceramic based meta-structure design method could extend to more high temperature EM manipulation applications. © 2020 Elsevier B.V.