Fourier transform solution of split-step Padé parabolic equation

As a wide angle paraxial approximation, split-step Padé parabolic equation (SSP-PE) gives exact solution to wave propagation involving large propagation angles. Considering non-uniform refractive index, it is difficult to solve SSP-PE using Fourier transform. In general, SSP-PE is computed using finite-difference method. However, it is rational to ignore atmospheric refraction for radar cross section(RCS) calculation and short-range propagation, and then the Fourier transform solution of SSP-PE can be derived, which is presented in the paper. The Fourier transform method is more efficient than finite-difference codes. Numerical result with perfect electric conductor boundary condition is provided and is compared with the geometric theory of diffraction.