Fully analytical design of electromagnetic transmissive metagratings for highly efficient extreme-angle beam refraction and reflection

Metagratings are promising candidates for extreme-angle beam manipulation, due to two main features, namely, the ability to maintain very high efficiency in beam manipulation at extreme angles and the simplicity of the sparsely arranged structure for an easy physical implementation. Here, we propose to design transmissive metagratings, which can achieve highly efficient extreme-angle beam manipulation under normal incidence using a fully analytical design methodology, where information about the positions and impedance density values of the meta-atoms are derived from closed-form expressions. The design methodology is verified by full-wave simulations for extreme-angle anomalous refraction and reflection, where the simulations results are found to be consistent with the theoretical predictions. Proof-of-concept prototypes are fabricated and experimental demonstrations performed around 10 GHz are found to be in good agreement with the simulation results. The proposed metagratings open the door to high-efficiency functionalities in far-field beam manipulations and wireless power transfer.