A Study on the Conditions for Generation of Monopole Ultrasonic Pulse by Piezoelectric Polymer Film Transducers

Abstract

Short monopole ultrasonic pulses can be radiated from piezoelectric polymer film transducers driven by a step-function voltage with a fast rising time and low output impedance. In this study, we investigated the conditions for transmitting a monopole ultrasonic pulse by simulation and experiment. We clarify that the length of the pulse width is limited by transmission time ( T h ) in the direction of the thickness of the film transducer. By the simulations and experiments with the received pulse by changing the acoustic impedance of the backing material, it was also found that the backing material should be matched when the rising time of the driving step-function voltage is shorter than T h . It is also shown that the source impedance of the driving circuit is an important factor in generating short ultrasonic pulses.