Reconfigurable polarization conversion metasurface based on an air–dielectric composite structure

Abstract This paper presents a mechanically reconfigurable polarization conversion metasurface based on an air-dielectric composite structure. By integrating an adjustable air gap between a patterned metallic layer and a ground plane, the proposed design enables versatile control of electromagnetic waves without the need for complex active components or bias networks. Numerical simulations and experimental results demonstrate that the metasurface enables switching between linear cross-polarization conversion (LCPC) and linear-to-circular polarization conversion (LCPCC) within the frequency range of 14.48–23.67 GHz, corresponding to a fractional bandwidth of 48.17%. In the LCPC mode, the polarization conversion ratio exceeds 98%, while the axial ratio remains below 3 dB in the LCPCC mode. Physical analysis reveals that the mechanical modulation of the air gap primarily regulates the reflection magnitude while maintaining stable phase conditions, thereby simplifying the functional switching logic. Furthermore, by using a mirror-image unit cell arrangement, the design is successfully extended to enable switchable radar cross-section (RCS) reduction, achieving an average RCS reduction of over 10 dB across 12.0–23.6 GHz. With its advantages of low loss, structural simplicity, and high efficiency, this design shows potential for future applications in adaptive satellite communications and smart stealth systems.