Design of Narrow-Beamwidth Transducers

The design of focused transducers used to narrow the beamwidth over a finite distance in the nearfield region is outlined. A computer program was used to optimize the transducer's geometrical shape for beamwidth improvement, and off-axis computations for plane and focused transducers were programmed to check the improvement in beamwidth so obtained. The results of these computations show that a simple parameter can be used to describe and compare the degree of focusing of such transducers.