Accession Number : ADA020060

Title :   Radiation Pattern Shaping of a Two-Element, Concentric Ring Transducer Using Phase and Amplitude Shading.

Descriptive Note : Master's thesis,

Corporate Author : NAVAL POSTGRADUATE SCHOOL MONTEREY CALIF

Personal Author(s) : Shaw,Albert Hampden Proctor

Report Date : DEC 1975

Pagination or Media Count : 99

Abstract : A high-frequency transducer which gives usefully uniform radiation into a half space is required for use as a target locator in an underwater acoustic range. Phase and amplitude shading of a two-element transducer consisting of a central circular piston and a concentric annular ring has been proposed to meet the requirement. A transducer resonant at 74 kHz but scaled in terms of wave length to 25 kHz in the transverse dimension has been constructed and tested at both frequencies. Exceptionally wide radiation patterns with major lobe widths of the order of 150 degrees (10dB down) were obtained. At the scaled frequency computer model predictions based on simple theory agreed well with the measured radiation patterns. At the resonant frequency, however, predicted secondary lobe details were not found in the patterns. These discrepancies have been attributed to the non-uniform motion of the radiating surfaces due to mutual coupling effects through the transducer structure and the transmission medium. In spite of these minor problems associated with the prototype transducer, promising results have been obtained and have shown the design concept to be a valid and viable one. (Author)

Descriptors :   *Electroacoustic transducers, Rings, Hydrophones, Underwater tracking, Underwater vehicles, Acoustic ranges, Radiation, Patterns

Subject Categories : Electrical and Electronic Equipment
      Acoustic Detection and Detectors
      Acoustics

Distribution Statement : APPROVED FOR PUBLIC RELEASE