| Popis: |
An experimental study designed to detect and measure the contribution of creeping waves to the acoustic field backscattered by simple geometric bodies was performed. The tests utilized acoustically hard models of cylinders, spheres, and prolate spheroids irradiated in air, where a very good approximation to the ideally rigid case can be obtained. The various scattering components were separated both by the use of pulse/gating techniques and by comparisons of data taken with a range of incident pulse lengths. Although some evidence of creeping wave effects was noted near the model surfaces, the expected backscattered components could not be found in the returned field of any of the models. These results seem to reduce the practical significance of the concept of creeping waves as diffraction rays which interfere with specular and edge‐formed rays to create the total backscattered field. [Work supported by NAVSEA.] |
