Efficient Numerical Algorithm for Solving Scattering and Inverse Scattering Problems of Electromagnetic Waves

摘要

The development of an efficient numerical algorithm of determining the unknown material composition and shape of an arbitrary target from the measured electromagnetic waves in the far field region will enhance the capability of the defense radar system to defeat known evasive schemes. The first step in this research effort is the development of an efficient and versatile numerical algorithm for calculating the scattered electromagnetic waves/radar cross section by a target with known complex geometry and material property. Hence the purpose of this Phase I research is to develop an efficient numerical algorithm for solving two dimensional scattering problems. This is achieved by using a special finite difference method based upon a natural spatial discretization of the integral form of Maxwell's equations on a non-orthogonal grid-system and the leap-frog finite differencing in the time domain. It has the advantages of being (a) more efficient than other known numerical methods, (b) highly accurate due to the body-fitted grid system, and (c) the easiest numerical method to implement boundary conditions. The capability and feasibility of this two-dimensional computer code are tested by performing numerical simulations on few realistic examples, e.g., cylindrical objects with cross sections of metallic jet and a composite airfoil. In these processes, the radar cross sections as functions of both the incident angle and the scattering angle are calculated and they seem to be quite good. Hence this Phase I research is completed successfully. Keywords: Radar cross sections; Electromagnetic scattering.