Backscattering cross section of a rigid biconic reflector.
Plane wave incidence on a rigid biconic target is considered. A biconic reflector consists of two cones truncated by planes perpendicular to their axes and joined at their smaller flat faces. The cone angles are allowed to be variable, provided their sum is equal to 90 degrees. The backscattering cross section is expressed in terms of a surface integral of the geometrical acoustics field, which results from incident singly and doubly reflected rays. A saddle-point calculation gives a first-order high-frequency approximation in which the backscattering cross section is proportional to the incident wave number and a function of the angle of incidence, cone angles, and inner and outer radii of the truncated cones. This expression is algebraically complex but easy to implement numerically. Results are presented that exercise the parameters of the problem. An interesting result of the solution is that for fixed outer radii there is a nonzero optimum inner radius for backscattering strength. For broadside incidence on 45 degrees cones with equal outer radii, this optimum value is approximately equal to 11% of the outer radius.
Eisler
T J
TJ
Coast Survey Development Laboratory, NOAA N/CS11, Silver Spring, Maryland 20910, USA. thomas.eisler@noaa.gov
D000162:Acoustics; D006801:Humans; D008962:Models, Theoretical; D012542:Scattering, Radiation; D013010:Sonication