Optimization Strategy to Design Rotating Nonlocal Meta-Deflectors for Risley-Prism Antenna Systems

A new advanced optimization strategy is proposed to design high-performance rotating deflectors used in Risley-Prism concept for low-profile 2D-beam-steering-antenna system at Ka-Band. This new methodology combines two important ingredients: (1) the nonlocal near-field effect generated by the interactions among adjacent subwavelength elements and (2) a Bayesian learning-based global optimization algorithm for deriving the geometrical characteristics of the constituting dielectric pillars, driven by a design objective. This optimization strategy delivers superior performance compared to the traditional global optimization algorithms and requires fewer solver calls. In this scenario, the meta-deflector is specifically designed to efficiently operate for all rotation angles between 180° and 90°. The proposed solution provides remarkable performance across the entire Ka-band. Moreover, the numerical results show multiple advantages, mainly in enhancing transmission efficiency in the desired diffraction order and eliminating the cross-polarization.