Accession Number : AD0866892

Title :   Analysis of the Frequency Response of Simple Geometric Targets.

Descriptive Note : Technical memo.,

Corporate Author : TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS

Personal Author(s) : Shirley, D. J. ; Diercks, K. J.

Report Date : 04 MAR 1970

Pagination or Media Count : 49

Abstract : Measurements of the steady state frequency response and pulse echo forms of air- and water-filled aluminum spheres and cylinders in water are presented. These compare favorably with theoretical results computed by Hickling. The nondimensional frequency (ka) range is 24 < or = ka < or = 60. (ka is the product of the wave number, 2 pi/lambda, and the target radius, a.) Scattering paths defined by the targets' cross-sectional geometry are identified, and it is shown that it is constructive and destructive interference between the energy returned along the different scattering paths that generates the frequency response of the target as frequency is changed. Similarities in the backscattered echoes from spheres and cylinders at normal incidence due to similarities in the scattering geometry are described. Measurements of circumferential waves in spherical shells are presented. It is believed that these are the first reported for this target form. (Author)

Descriptors :   *GEOMETRIC FORMS), (*TARGETS, (*ACOUSTICS, TARGETS), MATHEMATICAL ANALYSIS, BACKSCATTERING, SPHERES, CYLINDRICAL BODIES, AIR, WATER, ALUMINUM, MEASUREMENT, SOLIDS, WALLS.

Subject Categories : Numerical Mathematics
      Acoustics

Distribution Statement : APPROVED FOR PUBLIC RELEASE