Anomalous Reflection of Acoustic Waves in Air with Metasurfaces at Low Frequency

Figure 1

(a) Schematic map of acoustic metasurface unit cell and (b) longitudinal section of the unit cell. The unit cell is composed of a cavity with acoustically hard walls, which is capped with a rigid circular ring. The inside of the ring is a clamped membrane, and the outside is an air gap.

(a)

(b)