One of the very pertinent problems in electromagnetics is the fast and accurate design and analysis of complex guided structures. Many such structures offer superior performance over traditional waveguide topologies in terms of efficient propagation and realization of novel and useful components. This book is designed to particularly address this need. Starting from the fundamentals of propagation behavior in hybrid structures, the book gradually develops an efficient time-domain algorithm for the full-wave analysis of such structures. The method is thereafter extended to the rigorous design of guided wave discontinuities and components. The large number of examples dealt with helps the newcomer to gain a good grasp of the subject and understand the full potential of the technique. At the same time, an experienced reader would discover how the robust and general analytical technique can be used as a highly accurate and useful tool for the electromagnetic analysis of complex structures that can also be extended to the efficient treatment of other complex guided wave topologies.