Characteristics of piezoelectric ceramic transducers tapered with exponential function

Tapered piezoelectric ceramics have been used in the ultrasonic transducers because of their wide frequency bandwidth characteristics. However, the changes in the characteristics for a ceramic with a tapered shape has not been investigated sufficiently. In this study, to estimate the performance of a transducer made from tapered ceramics with various shapes, we introduce a thickness function with a shape index g. Using this function, we analyze the power transfer function and the –3 dB bandwidth theoretically and experimentally. Our results show that the bandwidth is inversely proportional to the acoustic transfer power for increasing g-value. The radiation characteristics of the transducer were also measured. The experiments show that the dire ctivity of the acoustic field changed with the tapered shape and with the driving frequency. KCI Citation Count: 1