Design of a Two Absorption Band Rasorber Based on Split-ring Resonator and Lumped Resistor

In this work, a frequency a frequency selective rasorber with two absorption bands is proposed. This FSR have a double-layer structure, the top layer is an absorptive transmission/reflection surface (ATRS), and the bottom layer is a lossless frequency selective surface. The two layers are separated by a quarter-wavelength thick air spacer. By cascading the lumped resistance with the LC resonator and the band-pass FSS (which has a passband coincides with that of lumped resistance), a transmission window with two absorption bands can be achieved The rasorber exhibits a transmission band between two absorption bands. The lossy layer is achieved by introducing resistors into the resonator structure. Full-wave simulation results show that the proposed FSR achieves two absorbed-bands which are 11 GHz similar to 13.9 GHz and 19.5 GHz similar to 25.9 GHz respectively. The bandwidth is 4.1 GHz and 9.9 GHz, respectively. The proposed rasorber has a transmission window at around 18 GHz. This structure with transmission in certain frequency while absorbing radar signal in others is very useful for stealth application. It can be applied in radome technology and significantly reduce the monostatic and bistatic RCS.