Based On The Parabolic Equation Large Target (multi-) Station Rcs Method

The Method of Moments, FDTD Method and Finite Element Method are classical numberical methods in computing electromagnetic. These methods can not treat electrically large objects scattering very well, because of too long computing time and/or too much memory needed. The parabolic equation(PE) method provides fast and accurate solutions of electrically large objects and thus overcomes all those limitations. The time of treating electrically large objects scattering can be reduced greatly by using the parabolic equation method. This method overcomes the disadvantage of big errors of the results computed by the method of physical optics. The dissertation mainly focuses on the basic derivation and application of the parabolic equation method. The main studies are as follows:(1) The parabolic equation deduced from the wave equation is applied to compute the vector electric or magnetic fields by combining the boundary conditions on the scattering objects, which testifies its availability and establishes the theoretic foundation for solving electrically large objects scattering quickly.(2)Polarization effects are considered fully. The boundary conditions are simplified by the parabolic equation method( The electromagnetic scattering in three dimensions can be transformed to solution in two dimensions), which simplifies the compute of vector field and accelerates the computing speed.(3) The implementation of parabolic equation based on an implicit finite ?difference scheme of the Crank-Nicolson type simplifies the transition of matrix of the field in range, which improves the computing speed greatly as a result of the solution at each step obtained directly from that at the previous step by using the transition of tridiagonal matrix. The scattering field can be computed by using the perfectly matched layer(PML) to truncate the computing field in the transverse plane. The RCS of the objects can be computed by using Fourier transformation and Near-field/Far-field transformation.(4) By comparing the results of electromagnetic scattering from simple objects computed by the parabolic equation method with those computed by other methods (such as numberical methods and the method of high frequency approximation), we can find accuracy and quickness of this method and its limitations.