All-Angle Nonlocal Metasurfaces on Demand: Universal Realization of Normal Susceptibilities via Multilayered Printed-Circuit-Board (PCB) Cascades

Abstract: Embedding normal susceptibilities in metasurfaces (MS), in tandem with their tangential counterparts, greatly enriches their spatial dispersion. Particularly, judicious siphoning of the microscopic nonlocality associated with such enhanced meta-atoms facilitates global control over the MS response across the entire angular range, specifically at challenging near-grazing scenarios. In this paper, we introduce a rigorous closed-form methodology to realize such intricate mixtures of tangential and normal components via a highly practical platform -- printed-circuit-board- (PCB) compatible cascaded admittance sheets. To this end, we derive a universal all-angular link between this MS-level composite, which leverages macroscopic nonlocality of multiple reflections, to its underlying meta-atom-level susceptibilities. We demonstrate this scheme by devising a PCB all-angle-transparent generalized Huygens' MS radome and an all-angle perfect-magnetic-conductor (PMC) PCB MS. Validated in simulation and experiment, our results pave the path toward a new insightful paradigm for studying and engineering nonlocal metadevices, e.g., optical analog computers and spaceplates.