Dual-band Trifunctional Coding Metasurfaces Based on Independent Control of Transmission and Reflection

Abstract

With the rapid development of modern integrated systems, wireless communication, imaging, and sensing networks have increasingly higher demands for multitasking devices, whereas the single-function equipment cannot meet the integration requirement. Most recently, as an alternative for complex reconfigurable systems, polarization-driven and asymmetrictransmission-oriented meta devices have demonstrated promising prospects. However, most multifunctional metasurfaces can only meddle in electromagnetic waves within the half-space domain or a single frequency band for flexible wavefront variations, significantly limiting its information capacity. Herein, we propose a dual-band multifunctional phase-coding metasurface, which can operate via both transmission mode and reflection mode under opposite directions of incidence and polarization states. To expand the operation frequency band with both x and y polarization waves, an anisotropic hybrid coding array layer consisting of split-ring and cross-shaped resonators is inserted between two layers of orthogonal wire gratings. Low cross-talk of the proposed coding metasurface within dual bands makes it possible to provide 3-bit coding in the K band and 1-bit coding in the Ka-band, respectively. As a proof of concept, based on generalized Snell’s law, geometric optics, and convolution theorem, three distinct functions are integrated into a shared coding aperture, including beam focusing, scattering manipulation, and the reduced radar cross-section (RCS), respectively. The far-field scattering patterns obtained by CST Microwave Studio demonstrate the behavior of the diverse plane wave in each case and show a high consistency with the theoretical prediction results. The proposed coding metasurface can effectively realize full-space electromagnetic control and improve the capacity of the information channel, which could be developed for potential applications in multifunctional devices and integrated systems.