Transducers for Low-Frequency Communications

Abstract

Large scale underwater sound transmission (e.g., ocean acoustic tomography) requires transducers operating in the very low-frequency range (< 500 Hz) to cope with the unavoidable medium losses. The LF-projectors should be highly efficient in converting the driving electrical energy into powerful structural vibrations, and then in transmitting these vibrations to the outgoing acoustic field. Thus, those devices should have a very high source-level, and, moreover, they should operate in a broad frequency band, and at great depth if required. To facilitate their handling and/or installation on fixed or moving platforms they should also be not too bulky and as light-weight as possible. This paper reviews the present most interesting techniques for the realization of these LF-transducers, as well as the primary motor technologies as the secondary matching methods for maximizing transducer performance.