A three-dimensional broadband underwater acoustic concentrator

We propose a three-dimensional (3D) omnidirectional underwater acoustic concentrator based on the concept of an acoustic prison, which can realize a substantial enhancement of underwater sound signals in broadband ranges. This device mainly employs the non-resonant multiple reflection characteristics of the semi-enclosed geometric space, so it has a wide working frequency bandwidth. Compared with previously reported concentrators based on transform acoustic mechanisms, the structure is more simple and, most importantly, it can realize omnidirectional signal enhancement in a 3D space. Moreover, the working frequency band of this acoustic concentrator depends on the size of the concentrator, so it can be changed directly through size scaling, which is convenient for engineering applications. In general, the designed underwater acoustic concentrator has the advantages of a simple structure, scalability, large bandwidth of working frequency, and high signal gain. It has potential applications in underwater target detection and other aspects.