Flexural plate sound transducer having low resonant frequency

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference should now be made to the drawing figures, on which similar or identical elements are given consistent identifying numerals throughout the various figures thereof, and on which parenthetical references to figure numbers direct the reader to the view(s) on which the element(s) being described is (are) best seen, although the element(s) may be seen also on other views.
FIG.
1 illustrates a typical sonobuoy system in which the present invention may be employed.
Here, first and second sonobuoys, generally indicated, respectively, by the reference numerals 20 and 22 have been deployed in the sea, each sonobuoy including, respectively, buoys 24 and 26 containing electronic circuitry and batteries (not shown), sea anchors 28 and 30, and flexural plate transducers 32 and 34 disposed at the lower ends of interconnecting cables and suspension means.
Sonobuoy 20 serves as a projector, while sonobuoy 22 serves as a receiver.
It will be understood that sonobuoys 20 and 22 have been deployed by conventional means from an airplane, a helicopter, or a ship.
In use, flexural plate transducer 32 on sonobuoy 20 emits a sound wave 40.
Sound wave 40 is reflected from an underwater object, here a submarine 42, creating a sound wave 44 which is received by flexural plate transducer 34 on sonobuoy 22, that sonobuoy reporting the event via an RF signal 46 to a monitoring helicopter 48.
This configuration is referred to as a bi-static configuration.
However, if suitable control circuitry is provided, flexural plate transducer 32 is also capable to transmitting sound wave 40 into the water and receiving relection 44 from submarine 42, thus requiring only one sonobuoy.
FIG.
2 illustrates the construction of a conventional flexural plate transducer, generally indicated by the reference numeral 50.
Transducer 50 includes a cylindrical housing 52 having extending across the interior thereof, orthogonal to the major axis of the housing, a flexural plate 54.
In this case, housing 50 and flexural plate 54 are of one-piece construction, but the flexural plate could also be a separate element attached by conventional means to the housing