Acoustic wave transparency for a multilayered sphere with acoustic metamaterials.

By analogy with the electromagnetic wave, the acoustic transparency phenomenon is analyzed for a multilayered sphere with acoustic metamaterials. The neutral-inclusion concept is used to predict the transparency conditions in the quasistatic case, which are further confirmed by a full-wave analysis. The mechanism of the transparency is based on lowering the total-scattering cross section of the composite sphere. It is found that, to improve the transparency, the angle-dependent scattering cross section must also be minimized for all directions.