High-Power, Low-Frequency, Textured PMN-PT Underwater Projector

There is an ongoing need to improve the design of low frequency, high power, broadband sonar transducers for use in A-sized air-deployed sensors (A-sized sonobuoys). Desired improvements include increasing the power, increasing the bandwidth, reducing the size, reducing the weight, and lowering the cost. Historically, most low frequency, high power air-deployed sensors utilize flextensional or flexural transducers containing PZT-8 (Type III) piezoelectric ceramics for transduction. More recently, PMN-PT textured ceramics have been developed. This material has piezoelectric properties that approach those of single crystal ceramics, with the advantage that it can be fabricated in larger sizes at a more reasonable cost. These transducers will have higher coupling, lower impedance and can be driven to levels of 15 V/mil or higher which therefore produces more power per Volt of drive. A low frequency, high power transducer made with PMN-PT textured ceramics has the potential to increase the Source Level, SL, as much as 10 dB or more than a similar transducer that utilizes PZT for transduction. A transducer made with textured ceramic material also can be designed to be more compact, lighter, have a broader bandwidth, and higher effective coupling coefficient than one using PZT.