TARGET SCATTERING CALCULATIONS WITH THE PARABOLIC EQUATION METHOD

The parabolic equation technique is used to solve the Helmholtz equati on in the presence of scatterers of arbitrary shape, in two and three dimensions. The scattered field is computed directly, using non-homoge neous boundary conditions on the scattering object to represent the in cident field. Effectively this decouples the PE paraxial direction fro m the direction of incidence. For convex objects the whole range of sc attering angles can be covered with a small number of narrow-angle cal culations. Finite-difference implementations involve tridiagonal matri ces in two dimensions and more general sparse matrices in three dimens ions. The resulting codes can be used to solve scattering problems for objects ranging in size from a few wavelengths to hundreds of wavelen gths. The method has been tested against analytical solutions for soft and rigid circular cylinders in 2D and soft and rigid spheres in 3D, showing good agreement at all scattering angles. (C) 1998 Acoustical S ociety of America. [S0001-4966(98)03202-0].