Broadband tunable acoustic metasurface based on Helmholtz resonators

A broadband tunable acoustic metasurface (BTAM) is conceived with Helmholtz resonators (HRs). The tunability of HRs' neck enables precise control over the phase shift of the unit cell. Through careful arrangement of unit cells, the BTAMs are engineered to exhibit various phase differences, thereby inducing anomalous reflections and acoustic focusing. Numerical simulations demonstrate the BTAM's remarkable efficacy in manipulating the angle of reflection wave and achieving wave focusing across a broadband frequency range. Experimental investigations of the phase shift and anomalous reflection further validate the design of metasurface. This work contributes to the fields of broadband and tunable acoustic wave manipulation and provides a flexible and efficient approach for acoustic control devices.