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The flexural disk transducer has been recognized for many years as a viable candidate for applications requiring low‐frequency sound sources. Since the establishment of the theory by Woollett [“Theory of the Piezoelectric Flexural Disk Transducer with Applications to Underwater Sound,” USL Report No. 490, December 1960], much of the development effort has been directed toward improved fabrication and mounting techniques which have resulted in high electroacoustic efficiencies, increased power handling capabilities and greater correlation between theory and measurements. Programs to provide greater depth capability and improved bandwidths are continuing. The combination of specific requirements impose certain limitations upon the design of the flexural disk and dictate tradeoffs where possible. These limitations and tradeoffs are described as they relate to transducer applications at low frequencies requiring high acoustic‐source levels, broadband widths, and deep submergence operation. Two transducers have been fabricated, one below 100 Hz to demonstrate potential VLF applications and limitations, and another at 250 Hz for evaluation of the power capabilities of large diameter (33 in.) mosaic disks. The designs, test results, and a summary of possible design trade‐offs are presented.

An exact distributed electromechanical equivalent circuit is derived for purely cylindrical waves in an axially polarized piezoceramic thick walled hollow cylinder. The analysis applies to either stress free or clamped in the axial direction, and the theory may be used to account for losses.