Optimized Varactor-Tuned RIS Design for Wide-Angle Perfect Anomalous Reflection

Realizing the capability of scanning reflected beams to any arbitrary angle without parasitic scattering has become a technical challenge in designing efficient reconfigurable intelligent surfaces. In this work, we develop a varactor-integrated unit cell employing a capacitive-dominant impedance tuning technique and numerically demonstrate a subwavelength-spaced reflectarray at 13 GHz. The array is composed of passively loaded patch meta-atoms, and it is able to control the beam scan angle by accurately predicting and synthesizing the scattering characteristics, achieving nearly perfect scanning anomalous deflection.