Annular acoustic lens based on five-mode material

The invention provides an annular acoustic lens based on a five-mode material, the whole acoustic lens is composed of multiple layers of five-mode material unit arrays, and the center of the acoustic lens is filled with silicone oil. A traditional acoustic lens made of natural materials has the problems of single directivity, damage to an original sound field and the like, the limitation of the traditional materials is broken through, a five-mode material in an acoustic metamaterial is adopted, the coupling effect of a five-mode material structure and material parameters on equivalent properties is researched on the basis of the energy band theory and the conversion acoustics theory, and the acoustic lens is obtained. The equivalent density and the bulk modulus of each layer of five-mode material unit are in anisotropic distribution, and the annular acoustic lens based on the five-mode material is designed. By the adoption of the technical scheme, sound waves pass through the acoustic lens, the sound waves ar