Analysis Of Metallic EBG Structure And Waveguide Eigen-modes

Recently, the artificial metallic periodic structures have attracted intense attention because of the electromagnetic band gap (EBG) properties in microwave bands. The EBG structure provide good radiating and extremely low loss, so the EBG based microwave devices, are especially useful in high operating frequency and high power density cases, which lead to the tremendous application potential in both civil and military area. The analysis of band structure as well as the mode problem is the basis of EBG structure research.At first of this paper, the fundamental of photonic crystal will be introduced systematically based on Maxwell equations. Both plane wave expansion method(PWE) and finite difference in time domain method(FDTD) are deducted in detail. FDTD is a kind of almighty method, it can be use to simulate the operating statue as well as band structure.Subsequently,the group theory will be introduced to analysis of the period structure. The symmetry relations of two-dimensional photonic crystals are deduced by the method of group theory. And good consistency is shown between group theory and the numerical solutions from PWE.Based on the theory research work above, the metallic EBG structures are studied in detail. The two dimensional EBG structures are modeled by FDTD algorithm, and then the dispersion relations are computed. Besides, the guided modes in planar metallic EBG waveguide are found. Finally, the FDTD method is used to solve the mode problem of metallic EBG waveguide.The effects of defect size and thickness of waveguide are studied numerically. Then the mode patterns are computed by FDTD. It can be seen that symmetry characters of computed modes are same as that predicted by group theory. In the end, the dispersion relations of EBG waveguides are simulated based on the mode results.