A butterfly metasurface with efficient multi-functional polarization conversion operating in the Ku-Ka band

A highly efficient and multi-functional butterfly polarization conversion metasurface is proposed for the Ku-Ka frequency range, designed to reduce the radar cross-section. The suggested converter enables dual frequency bands linear-to-cross (LX) and linear-to-circular (LC) polarization transformations. The efficiency of cross-polarization conversion exceeds 90% over the frequency ranges of 14.57-16.30 GHz and 25.70-37.03 GHz, with relative bandwidths of 11% and 36%, respectively. Reflections of left-hand (LHCP) and right-hand circularly polarized (RHCP) waves are realized within the frequency ranges of 17.78-25.31 GHz and 37.38-37.73 GHz, with relative bandwidths of 35% and 0.9%. The oblique incidence significantly affects the metasurface conversion performance, and the proposed model manifests angular robustness up to 60°. Additionally, the butterfly metasurfaces are deployed in a triangular chessboard configuration to achieve radar cross section (RCS) reduction spanning the frequency bands of 14-15.17 GHz, 24.60-35.20 GHz, and 36.30-38 GHz. Drawing from simulation results and test-based validation data, the proposed converter holds promising applications in wireless communication, antenna engineering, and radar stealth.