Wide-angle nonlocal boundary conditions for the parabolic wave equation

Nonlocal boundary conditions offer a useful alternative to the traditional use of absorbing layers for implementation with parabolic equation computations. We set up nonlocal boundary conditions for use with the split-step Pade approximation of the parabolic wave equation. The great advantage of the resulting algorithm is that it solves wide-angle propagation problems without any loss of accuracy. Numerical results show that the propagation of plane waves is perfectly handled even when very large angles are involved.