Sound emission is inefficient at low frequencies as limited by source size. This letter presents enhancing emission of monochromatic monopole and multipole sources by enclosing the source with a subwavelength circular enclosure filled of an anisotropic material of a low radial sound speed. The anisotropy is associated with an infinite tangential density along the azimuth. Numerical simulations show that emission gain is produced at frequencies surrounding degenerate Mie resonant frequencies of the enclosure, and meanwhile the radiation directivity pattern is well preserved. The degeneracy is theoretically analyzed. A realization of the material is suggested by using a space-coiling structure.
|Original language||English (US)|
|Number of pages||1|
|Journal||The Journal of the Acoustical Society of America|
|State||Published - Jul 6 2017|
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: This work is supported by King Abdullah University of Science and Technology, and by the University of Mississippi through the start-up fund and the 2017 College of Liberal Arts Summer Research Award.