Flextensional transducers are known in the art. One type of flextensional transducer has a flexible outer shell and a piezoelectric stack of elements. When actuated, the stack expands and contracts, thereby flexing the shell. The shell is coupled to and projects acoustic energy into an acoustic medium, such as water. Such transducers are limited by the amount of prestress that can be imposed on the piezoelectric stack to avoid exposure to tensile stress. The characteristics of the transducer are variable with depth in the acoustic medium. In general, the maximum depth of operation of the piezoelectrically driven flextensional transducer is governed by allowable ceramic stress and performance degradation.
Another type of flextensional transducer uses a magnetically driven element, which employs a moving coil in a magnetic field instead of the piezoelectric stack. The transducer shell is driven by energizing the coil which flexes the walls of the transducer inwardly or outwardly.