Validation of Extended Kirchhoff Approximation and Small Slope Approximation for electromagnetic scattering from ship wake surfaces

Extended Kirchhoff approximation and small slope approximation are employed to calculate the normalized radar cross-section of ship wake surfaces. Method of moments accelerated by the multilevel fast multipole algorithm is adopted to test the accuracy of the two analytical approximate methods. Numerical results show that the two approximate approaches can extract reliable results unless at large scattering angles, which permits us to simulate the scattering from extremely large wake surfaces.