Very High Powered, Low Frequency Underwater Projectors

There is an ongoing need to improve the design of low frequency, high power sonar transducers for use in ASW applications. Desired improvements include lowering the frequency, increasing the power, increasing bandwidth, reducing size, reducing weight, and lowering cost. Most low frequency, high power transducers for ASW applications currently utilize flextensional transducers containing piezoelectric PZT type ceramics that are typically field limited, not stress limited. Single crystal piezoelectric ceramics have been investigated as possible improvements to PZT for transduction, because they enhance transducer performance with higher effective coupling, lower Q, and wider bandwidths. A major drawback, however, is that they are costly and are size restricted which limits low frequency and high power usage.More recently, Textured PMN-PT ceramics have been developed. This material has piezoelectric properties that approach those of single crystal ceramics, with the advantages that it can be fabricated in larger sizes with lower cost and can be driven at higher drive levels. Therefore, a transducer made with this material has the potential to produce more source level and can also can be designed to be more compact, lighter, have a broader bandwidth, and higher effective coupling than one using PZT.