Design and development of a constant beamwidth transducer for sub-bottom acoustic profiling

The design, fabrication, and acoustic calibration for a new Constant Beamwidth Transducer (CBT) is presented. Although designed for a sub-bottom profiling application, the transducer may be used whenever a spatially constant sound beam is desired over a relatively wide frequency range. The CBT design is based on the theoretical work presented earlier by Van Buren et al. (1983) and relies on an axis-symmetric velocity distribution acting over a spherically curved surface. The velocity distribution follows a Legendre shading function that is accomplished by dividing the surface electrode pattern into several discrete concentric rings. Design theory, fabrication, and measured results for a prototype transducer are presented