| It has been a great challenging task for years to solve complicated electromagnetic problems in an efficient and accurate manner, especially by using analytical approaches. With the rapid development of modern computer technologies and techniques, it has become possible to solve the Maxwell's equations involving complicated geometrical structures by using numerical methods. The Finite Difference Time Domain (FDTD) algorithm, originally introduced by K. S. Yee in 1966, has provided a powerful and robust tool for a wide category of electromagnetic applications. The objective of the research is to develop a generalized non-uniform FDTD Maxwell's solver under the cylindrical coordinates, and to further apply it to the analysis and design of various cylindrical monolithic millimeter-wave integrated circuit (MMIC) structures.; In this work, an efficient non-uniform mesh-generating algorithm is developed, which improves the efficiency of FDTD algorithm and saves computing resources significantly. The anisotropic perfectly matched layer (APML) is also investigated and employed for mesh truncation of open structures in the computational domain. In particular, as a very important part of this research work, a unified non-uniform cylindrical FDTD (NU-CFDTD) algorithm is developed. With comparison to traditional FDTD methods, the proposed algorithm requires no need for splitting a computational volume into FDTD and absorbing boundary condition (ABC) regions, and is designed to be easy for coding and flexible in treating various materials without adding computational resources. In this thesis, the NU-CFDTD computed results for a number of practical structures are validated with comparison to analytic solutions, experimentally measured results, or those obtained from published literatures.; In addition, the research includes intensive analysis of various cylindrical microstrip-type structures and design of practical MMIC structures, such as single-layer and multi-layer integrated printed low-pass filters. As the final part of this thesis, the proposed NU-CFDTD algorithm is extended and applied for the analysis of scattering and antenna problems in the cylindrical coordinates. |
