Airborne broad-beam emitter from a capacitive transducer and a cylindrical structure

Abstract

Beamwidth broadening of an ultrasonic air-coupled transducer is performed by an emitter constituted of an electrostatic transducer and of a cylinder with an opening at the top covering the surface of the transducer. The acoustic emission is thus forced through a hole smaller than the diameter of the transducer’s surface. In particular, a cylinder with an upper diameter of 10mm and a height of 5mm ensures the beam pattern of the final emitter is broad across a wide frequency range. Sound attenuation is reduced and lobes in the transducer’s beam pattern are cancelled. Beam broadening can improve range estimation techniques and ultrasonic sonar as a wider area can be inspected with one emission with no need for scanning