Subwavelength Monopole Underwater Sound Radiator.
DEPARTMENT OF THE NAVY WASHINGTON DC
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A compact subwavelength size monopole underwater sound radiator has characteristics to maximize resistive radiation impedance, minimize reactive radiation impedance, facilitate heat dissipation and minimize compensating air usage. This results in improved efficiency, bandwidth and use factor. The underwater sound radiator uses two back-to-back mounted, frustum shaped, hollow, radiating shells to achieve radiation characteristics approximating those of an equivalent sized pulsating sphere. An elliptically shaped, uniform cross-section magnetostrictive ring crossed by a linear piezoelectric spreader comprises a compact electric driver. Both the magnetostrictive ring and the piezoelectric stack contribute to the output through inverse phase cyclic changes in their respective lengths those changes being added and amplified by the flexural-bow type action of the elliptically shaped magnetostrictive ring. Air maintained at the pressure of the surrounding water fills an elastomer walled tube which is routed in close proximity to appropriate interior radiator surfaces. This provides a compressibility function with an oil-filled radiator. The oil transfers heat from the driver to the water cooled radiator structures.
- Acoustic Detection and Detectors