Electromagnetic Scattering Analysis Of 2-D Objects With TDFEM

In this thesis, The Volumetric Excitation (VE) method in Total- and Scattered-Field Decomposition (VETSFD) techniques is applied to Time Domain Finite Element Method (TDFEM) for electromagnetic scattering analysis of some representative 2-D objects. Firstly, TDFEM is introduced, and the theory and the steps of electromagnetism analysis are given. Secondly, to mitigate dispersion error on the incident wave, while preserving a total-field region local to the objects of interest, the whole computational area is split into Total Field (TF) and Scattered Field (SF) with connecting boundary (CB), and the incident wave is impressed on the TF. The Mur absorbing boundary condition (ABC) is used to truncate the computational area. To validate the accuracy of the VETSFD-TDFEM, the leakage in the computational area in absence of objects is investigated firstly. The maximum leakage of backward scattering into the scattered-field region is about -110 dB, which is much more accurate than the traditional Huygens'surface excitation method (the associated wave leakage is as high as -20dB). Then the far filed can be obtained from the electromagnetic field distribution on output boundary (OB) lies between CB and AB according to the equivalent theory. Radar Cross Section (RCS) of some representative 2-D objects can be obtained.And then, the scattering of transverse electric (TE) field mode is investigated in this paper, The bistatic RCS of some metal objects, medium objects, dielectric coated metal and metal airfoil are computed and presented. The numerical results generated with VETSFD-TDFEM are compared with the results simulated with FDTD or reference results, which demonstrates that VETSFD-TDFEM is an effective method for electromagnetic scattering analysis of complex objects. Besides, computational time, memory consumption, stability of iteration and computational precision are also investigated in this paper.Finally, the electromagnetic scattering of a special photonic crystal-the finite periodicity micro-structure of Morpho butterfly's wing is analyzed with VETSFD-TDFEM. The bandstop and angle-dependent characteristics of the micro-structure are investigated in detail in this paper.