Design of Polarization-Insensitive Multilayer Absorber for Ultra-Wideband RCS Reduction

This paper proposes an ultra-wide and polarization-insensitive multilayer absorbers by combining frequency selective surface (FSS) and absorbing material. The structure is composed by three layers which are FSSs loaded with resistors and absorbing material at the bottom and each layer is separated by air. The FSS in bottom has good absorption performance at high frequency while the upper layer is used to achieve low-band absorption. In order to extend the absorption band to the low frequency further add a layer of absorbing material at the bottom. The simulation results show that an ultra-wide absorption band from 0.61 to 12.33 GHz with a fractional bandwidth of 181% is realized under the normal incidence. Furthermore, the thickness of the structure is only 0.07λL, where λL represents the wavelength of the minimum operating frequency. The designed absorber is fabricated and measured, and the measurement is in good agreement with the simulation.