Design Method of Broadband Acoustic Metasurfaces Based on the Transmission-line Theory

The design method with a non-resonant one-dimensional distributed transmissionline model for broadband electromagnetic metasurfaces is extended to acoustic metasurfaces and a broadband acoustic metasurface for refracting a normal incident acoustic plane wave is designed according to the introduced method. It is shown that we can theoretically determine the characteristic impedance and the line length for realizing the acoustic metasurface in the same way as in the case of electromagnetic metasurfaces. In order to confirm the validity of the introduced method, circuit simulations mimicking acoustic numerical simulations are carried out and the broadband operations of the designed acoustic metasurface are shown from the results of the complex voltage distributions corresponding to the acoustic pressure those.