A Dual-functional Metasurface for Simultaneous Microwave Absorption and Vortex Beam Generation Towards Enhanced RCS Reduction

With the rapid advances in radar detection and guided weapon technologies, military assets in modern warfare face a high likelihood of destruction once detected, making it imperative to minimize the radar cross section (RCS) of equipment. Scattering and absorption represent the two primary approaches for RCS reduction (RCSR). However, reliance on either method alone often encounters performance limitations, such as the reduced effectiveness of scattering techniques against multi-static radar detection. Herein, a microwave absorbing metasurface with integrated vortex beam generation capability was proposed, which achieves significant RCSR through the high-efficiency synergy of absorption and scattering. A capacitive metamaterial, composed of the square resistive film separated by an air spacer, serves as the core element for microwave absorption. Leveraging the integration of equivalent circuit theory and electromagnetic absorption theory, a structural library of absorber units was efficiently developed. Each unit within this library exhibits distinct structure parameters and reflection phase characteristics while consistently maintaining high-efficiency electromagnetic absorption. Subsequently, appropriate absorber units were selected from the structural library and strategically arranged to form the final dual-functional metasurface, satisfying the specific phase gradient requirements for vortex beam generation. For topological charge 1, three separate dual-functional metasurfaces were specifically designed, each targeting RCSR at 10 GHz, 12 GHz, and 14 GHz respectively. All three configurations demonstrated excellent performance, with the 14 GHz device achieving an outstanding RCSR of -34.19 dB at its target frequency. Furthermore, metasurfaces also demonstrated significant RCSR at 14 GHz when topological charges are 2, 3 and 4. This work effectively demonstrates a novel paradigm for RCSR through the synergistic integration of microwave absorption with vortex beam generation.