A novel approach for a bistatic scattering calculation suitable for sonar performance model

One of the classical approaches to the calculation of the sound pressure scattered from a rough surface is to sum the contributions to the field from a set of small tiles that approximate the surface. If the tiles are smaller than the wavelength, or infinitesimal, the Kirchhoff's, the Small slope and small perturbation approximations can give good results. However, these approximations are computational intensive. In addition, if the tiles are larger than the wavelength these approximations cannot be applied. This work proposes a novel approach to accurately calculate the bistatic scattering from a rough surface approximated by tiles larger than the wavelength. The theory behind the calculations includes both specular and off-specular scattering components with their correct amplitude contributions. The results of the new approach are applied to a sonar performance model and compared with high frequency data. The model-data comparison demonstrates the validity of the theory.