Metagratings on Low-Cost Substrates for Efficient Anomalous Reflection: Addressing Dielectric Loss

We present a theoretical framework and practical methodology for designing high-efficiency metagratings (MGs), sparse periodic arrangements of subwavelength polarizable particles (meta-atoms), on low-cost dielectric substrates with non-negligible losses. The formulation incorporates these losses and exploits multiple degrees of freedom to optimize beam manipulation efficiency within a simple realistic printed-circuit-board (PCB) configuration. Importantly, the various loss mechanisms are analyzed using a judiciously devised equivalent circuit model, providing insights on their respective contributions. We validate our theory by designing, fabricating, and experimentally characterizing an efficient FR4-based anomalous reflection PCB MG, demonstrating good agreement between analytical predictions, full-wave simulations, and laboratory measurements. This work opens avenues for realizing efficient, low-profile, beam manipulation devices at reduced cost, offering practical solutions to mitigate loss limitations in diverse material sets across the electromagnetic spectrum.