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

Figure 2

Reflected phases and ratios of the eight subunits as a function of . The wavelength of the incident wave is 600 mm. The red triangles and black dots refer to discrete phases and ratios of eight subunits having specific membrane radius (i.e., 18.97, 19.53, 19.70, 19.81, 19.91, 20.00, 20.20, and 21.00 mm, respectively). The phase shift between two adjacent subunits is 45°. The mean reflected ratio is 0.89, as shown by the dashed line.