Frequency-Tunable Meta-Atom Design with Angular Stability for Reconfigurable Intelligent Surface

In this paper, we develop a frequency-tunable, 2bit, angle-stable meta-atom design for RIS-assisted wireless communication, integrating the combined control of PIN and varactor diodes. The proposed meta-atom operates within the Sub-6 GHz spectrum, encompassing the N78 and N79 communication bands. By loading metallic vias, the angular stability of the phase response of meta-atom is significantly enhanced within an incidence angle range of up to 60°. To validate the effectiveness, we simulate and analyze the far-field patterns of angle-stable and angle-dependent metasurfaces with identical size and periods. The simulation results demonstrate that angle-stable metasurface can effectively suppress the energy levels in undesired directions. Therefore, this design enhances communication quality and reduces interference with unrelated users in single-user communication scenarios, showing potential applications in next-generation wireless communication systems.