Spectral propagation algorithm for RCS of perfectly conducting cavities

An iterative spectral propagation algorithm is developed which introduces new features that improve the numerical efficiency and accuracy of the spectral iteration technique and the spectral incremental propagation procedure. The new spectral algorithm is particularly useful for analyzing closed problems where the boundary structure is too large for low-frequency matrix methods and too complex for high-frequency approximations. The scope of application includes the radar cross section of cavities, waveguide discontinuities and filters, and conformed or corrugated horn antenna analysis. The method is also valid for scattering problems in free space, but the continuous spectrum of nonperiodic fields together with the periodicity of the discrete Fourier transform require a very high number of field samples. For that reason, the efficiency of the algorithm may be worse than that of matrix methods for very complex scatterers and worse than that of high-frequency methods for large and simple objects. The main drawback is that boundary conditions are restricted to perfect electric or magnetic conductors, so that electric loading cannot be considered.<>