MULTIFREQUENCY TRANSDUCERS FABRICATED USING PZT P(VDF-TRFE)-1-3 COMPOSITE/

A multifrequency composite ultrasonic transducer system is described. The transducer consists of lead zirconate titanate (PZT) piezoelectric ceramic cylinders embedded in a vinylidene fluoride/trifluoroethylene (P(VDF-TrFE)) copolymer matrix. Both phases are piezoelectrically act ive. By selecting an appropriate height to diameter ratio for the cera mic cylinders, the transducer can be made to resonate at a number of f requencies. The frequency of the resonance arising from the copolymer matrix depends on the composite thickness. The other resonance frequen cies are determined by the height to diameter ratio of the ceramic cyl inders. A number of multifrequency transducers have been constructed a nd the observed resonance frequencies agree well with the predictions, based on the mode coupling theory.