| This dissertation involves the formulation, analysis, and application of higher-order accurate methods in the context of electromagnetic problems. Higher-order finite-difference time-domain (FDTD) schemes are examined and implemented into three-dimensional general codes which can handle arbitrary geometries and can perform numerous types of analysis, such as antenna, coupling, and penetration analysis. Specifically, a second-order accurate in time and fourth-order accurate in space scheme FDTD(2,4) is mainly used throughout this dissertation. In order to solve “open-space” problems, absorbing boundary conditions (ABCs) are formulated and applied in the context of FDTD(2,4). Various difficulties with the implementation of higher-order schemes, such as boundary conditions and discontinuities, are extensively discussed and resolved. Two different hybrid techniques between standard subgrid FDTD(2,2) and FDTD(2,4) are formulated and applied to various problems.; Furthermore, spectral and pseudospectral methods are formulated and applied to electromagnetics problems. Numerous codes are developed in the context of the spectral methods to implement entire- as well as multi-domain approaches and PML.; Another main objective of this dissertation is to analyze two very important and complex practical problems. The first problem concerns the analysis of cavity-backed slot (CBS) antennas with particular emphasis on different coupling reduction techniques. A very comprehensive study of coupling between two CBS antennas is also performed through measurements and simulations. The second problem involves shielding effectiveness analysis into conducting enclosures via apertures, and it relates to penetration of High Intensity Radiated Fields (HIRF) into airplane fuselages. Various acceleration techniques are presented. Finally, the third problem involves analysis of interference generated by personal electronic devices (PEDs) inside air-frames. |
