Research on acoustic wave manipulation based on subwavelength fence structure

Acoustic metamaterials have been the focus of research in recent years. By designing the unit structure of materials at the sub-wavelength scale, materials have unprecedented special properties, such as the realization of acoustic beam collimation. However, in previous studies, these collimated acoustic beams either have strong sidelobes, or the structure of the metamaterials is complex and difficult to verify experimentally. In this paper, we propose a simple fence-structured unit that, after periodic arrangement, excites collective surface oscillations in a specific frequency band to achieve an acoustic beam collimation with almost no sidelobe, which is verified by numerical simulations and experiments. This structural unit provides an effective means for directional sound propagation in air.