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Description
Subwavelength corrugated surfaces (SCSs) provide a compact and broadband approach for planar acoustic focusing, enabling efficient wavefront manipulation without relying on bulky curved or refractive elements. While the focusing capabilities of SCSs have been demonstrated experimentally and numerically, a systematic understanding of how geometric parameters influence focal efficiency and operational bandwidth is lacking. This work presents a parametric analysis of planar focusing SCS configurations, introducing the Focal Concentration Efficiency metric to quantify the fraction of acoustic power localized near the focal point. Simulations based on both a full-wave model and a reduced-order phased-array model are employed to explore the effects of groove number, spacing, and overall surface dimensions over a broad frequency range. The results reveal clear geometry-driven trends, highlighting intrinsic efficiency limits and providing practical guidelines for the design of compact, broadband SCS-based acoustic focusing devices.