Pulse and frequency responses of broadband low frequency ultrasonic transducers

Abstract

In this article investigation of low frequency broadband contact type ultrasonic transducers is described. A few types of the driving pulses were used in the frequency range from 50 kHz up to 350 kHz. Numerical simulations and experimental investigations were performed. The main dependencies of the frequency responses are in a good coincidence for both cases. The spectrum magnitude of the three periods of the driving pulse has the bandwidth of lobes 3 times narrower than the in the case of a single driving pulse. The ultrasonic transducers with and without the replaceable protectors were investigated. It was obtained that the first period of the pulse response possesses high steepness suitable to be used for time of flight measurements. The second and the third periods of the signal are wider due to compression type vibrations of the piezoelement. The convex replaceable protector gives additional losses of ultrasonic signal and changes the frequency response giving the extra minimum values at some frequencies. Keywords: frequency response, replaceable protector, pulse response, contact type scanning, broadband transducer.