Directional acoustic source by scattering acoustical elements

Highly directional sources are desirables in a variety of fields for many applications. The authors report an inverse designed scattering acoustical element device that transforms an omnidirectional ultrasonic source into one highly directional. This two-dimensional design shows an overall better modeled performance than other previously proposed, including a half-power angular width less than 5°. The experimental demonstration is performed in the ultrasonic range, using a hydrophone as omnidirectional source and an array of alumina rods as building blocks for the scattering acoustical elements. The measured half-power angular width is 6°, a value that supports the high reliability of the designing tool.