RADIATION-PATTERN OF A FOCUSED TRANSDUCER - A NUMERICALLY CONVERGENT SOLUTION

The radiation pattern of a focused transducer is reexamined. The radia tion field is divided into an illuminated zone and a shadow zone. A nu merically convergent solution of the pressure distribution in terms su mmations of Bessel functions is provided. This solution is computation ally more advantageous than earlier results where a double or single i ntegral in the complex plane is required. The pressure amplitude diffe rs from earlier reports slightly for off-axis locations at low frequen cy. This difference may have significance for backscatter coefficient determination where scatterers are assumed present over a time-gated v olume. The solution for a flat disk radiator is obtained as a limiting case.