Tunable directional subwavelength acoustic antenna based on Mie resonance.

Modulating the emission pattern of classic sound sources with a sub-wavelength scale dimension is a challenging. In this letter, we demonstrate theoretically and experimentally that a Mie-resonance based antenna can be designed in various modes to effectively enhance the emissivity of the radiated power and directivity of radiation pattern. A 2.33-fold enhancement of the radiated power and an 8.93-fold enhancement of the sound intensity are achieved in the mainlobe direction. Furthermore, we propose reconfigurable antenna scanning where the selectable beam direction is free to be controlled from 0° to 360°. The tunable directional acoustic antenna offers a new way to control sound with the improved performance.