Improvement on the Forward-backward Iterative Physical Optics Algorithm Applied to Computing the RCS of Large Open-ended Cavities

The method of initial value succession is introduced to the forward-backward iterative physical optics (FBIPO) algorithm. The initial residual error is reduced by inheriting the current values. Combined with a relaxation parameter, the method improves the convergence of the FBIPO algorithm for cavity scattering problems. The accuracy of RCS calculation is also enhanced by using a more precise mixed-face model. Then, the RCS of a jet inlet model is calculated, with its results in good agreement with the experimental ones. The method is also used to calculate the RCS reduction of a circular waveguide by coating the inner wall with a thin absorber layer.