engleski

Estimating ultrasound transducer parameters using KLM equivalent circuit model

Calculation scheme for estimating ultrasound piezoelectric transducer parameters in form of KLM equivalent circuit has been implemented in MATLAB and used to characterize transducer before its physical construction. Input parameters for equivalent circuits have been found using impedance data measurements of piezoceramic samples as free resonators. Equivalent circuits enable flexible estimation of input impedance of transducer system and gives approximately transfer function of the system in frequency domain near thickness extensional (TE) mode. Transfer function can be given as a ratio of radiated pressure, surface velocity or force (on active surface) and applied voltage in frequency domain. Several configurations of transducers have been made from PZT-5A ceramic of different thickness and diameter for studying influence of ultrasound field on human tissue. Transducers were constructed as systems with active piezoelectric element, n&middot ; ; ; ; λ /4 matching element section in front of active element face (made from perspex), air-backing on back face, and cable. Estimated input impedance of ultrasound system radiating in water depending on frequency using KLM equivalent circuit model is compared with measurement results in frequency range near TE mode of constructed ultrasound transducers configuration. Measured and theoretical conductance is used for calculating available bandwidth of constructed transducers. Transfer function as ratio of force (or pressure) on surface and input voltage is estimated with theoretical KLM model.

ultrasound transmitters; piezoceramic PZT-5A element; front-layer element; KLM model

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