| Summary: | Experimental measurements at near normal incidence of the underwater acoustic backscattering from a pressure release model rough surface with Gaussian statistics were conducted in a laboratory tank. Scattering measurements were obtained over the frequency range 20-1200 kHz, for a variety of transmitter and receiver positions. To obtain a source that has sufficient directivity and a wide enough bandwidth performance, to carry out the investigation, advantage was taken of the parametric array's unique properties. Theoretical expressions for the mean intensity were developed, using the Helmholtz-Kirchhoff Integral. The Fresnel and Fraunhofer phase approximations were used to evaluate the scattering integral, and predictions for the mean intensities were compared with the measured values. The Fresnel approach gave scattering coefficients which were in closer agreement with the experimental values.
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