I am working on sonar myself. Its hard to find information. I have found the following article that is very interesting. I hope this helps
Scientific American 271.n2 (August 1994): pp90(3).
Author(s): Kyle M. Becker.
Document Type: Magazine/Journal
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Abstract:
A simple, inexpensive marine transducer can be built out of a piezoelectric ceramic called zirconate titanate and common electrical equipment. Tips on building, calibrating, and using an underwater scanning transducer are provided.