Patent ID: 8121330
Filing Date: 2012-02-21
Classification: H04R

Abstract:
1. A phase plug, comprising a body having an input side for receiving acoustic waves and an output side for transmitting acoustic waves, the body including a plurality of channels extending from the input side to the output side for propagating acoustic waves through the body, wherein the input side comprises an input surface which includes a plurality of openings constituting entrances for the channels, the input surface being substantially part of a sphere or an ellipsoid in shape, and wherein the areas of the openings vary with radial position on the input surface, the radial position being measured in a direction extending perpendicularly from a central axis extending through the input surface, the variation in the areas of the openings being substantially proportional to a function in the range r·cos½Φ to r·cos2Φ, where r is the radial position and Φ is an angle subtended at the centre of the sphere or a focus of the ellipsoid between the central axis and the radial position.