Realization of acoustic omnidirectional radiation with annular anisotropic zero-density metamaterial

Acoustic metamaterials are artificial structures with unique properties that offer great flexibility for manipulating acoustic waves. In this manuscript, we describe the fabrication of an annular anisotropic metamaterial with an azimuthal effective density approaching zero and demonstrate its robust omnidirectional radiation performance. Locating two sources at a distance from one another or placing a cross-shape obstacle between them inside the cavity of the metamaterial produces acoustic omnidirectional radiation over a wide frequency range. This is quite different from the behavior in the cavity mode. This anisotropic zero-density metamaterial can be considered as a source shifter, which may have applications in acoustic manipulation, acoustic communication, cloaking, and sonar systems. Published under license by AIP Publishing.