Planar Absorbing FSS Unit Cells for Radar Cross-Section Reduction

This paper investigates proposed unit cell designs for absorbing FSS intended for radar cross-section reduction. For such applications, the design should fulfill two requirements. The first is there should be a conducting ground plane that represents the surface of the object whose RCS is wanted to be reduced. Moreover, the thickness of the absorbing FSS should be kept minimal. Three designs of the double square rings were proposed to obtain a low reflection coefficient and wideband and investigated using the CST Microwave Studio Suite. The FSS cell of a closed outer ring plus a split inner ring showed the best performance (0.132 GHz bandwidth at -10 dB reflection) compared to the conventional double closed rings, and the proposed meandered double ring cells. The three designed FSS cells have a small thickness of only 0.016 λ.