Study On The Time-domain And Frequency-domain Methods For Electromagnetic Scattering

In this thesis, the method of moments (MOM), the time domain integral equation (TDIE) method, the frequency-domain and time-domain equivalent edge currents methods and their applications are studied. The main works and results are as follow:1. The numerical procedure for treating problems of scattering by 3-dimensional dielectric bodies using the method of moments (MOM) is presented in detail. By numerical results, the major influencing elements for the Radar Cross Section (RCS) calculations of dielectric bodies are discussed.2. The mathematical thought and principle of the time domain integeral equation (TDIE) method are studied and based on the combined field integral equations, the iterative formulas of TDIE-MOT approach for solving the electromagnetic scattering from arbitrary shaped, three-dimensional dielectric objects are inferred and the way of calculations of transient far-field is presented. By the numerical results, instabilities of the Marching-On-Time (MOT) approach in TDIE are discussed. Still numerical results indicated that compared with MOM-IDFT, TDIE is more efficient.3. The procedure for solving electrically large electromagnetic scattering problems for equivalent edge currents (EEC) method is discussed. Method of the analysis of impulse scattering using EEC associated with the inverse discrete Flourier transformation technology (IDFT) is studied.4. Based on the inverse Fourier transformation of frequency-domain equivalent edge currents expressions, the time-domain equivalent edge currents (TD-EEC) method is developed. The time-domain diffracted field is expressed in terms of a contour integral along diffracting edges for an arbitrary incident field with proper delays. The TD-EEC numerical results are compared with EEC-IDFT results.