《Equivalent circuit for broadband underwate transducer》.pdf

IEEE TRANSACTIONS ON ULTRASONICS , FERROELECTRICS , AND FREQUENCY C ONTROL , vol. 55, no. 9, SEPTEMBER 2008 2079 Correspondence Equivalent Circuit for Broadband plications. Marshall and Brigham [5] have estimated the Underwater Transducers equivalent circuit parameters of transducers with a low figure of merit. They have determined 4 parameters of the R. Ramesh and D. D. Ebenezer equivalent circuit from the analysis of capacitance curve. Sherrit et al. [6] have proposed an equivalent circuit model Abstract—A method is presented to determine the equiva- of a piezoelectric thickness-mode vibrator and estimated lent circuits of broadband transducers with 2 resonances in the the circuit parameters from complex material coefficients. frequency band of interest. The circuit parameters are refined Church and Pincock [7] have described a method to deter- by least-squares fitting the measured electrical conductance data with this model. The method is illustrated by computing mine the equivalent circuit parameters of small acoustic the conductance and susceptance of the equivalent circuits of transmitters at or near resonance. However, these analy- 3 types of broadband transducers and comparing them with ses are restricted to transducers with one resonance in the the measured values. The equivalent circuit of a transducer is operating band of interest. Coates and Maguire [8] have necessary for designing filters that match the impedances of derived approximate expressions of equivalent circuit pa- the transducer and the p