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While there are many excellent books available on fundamental and applied electromagnetics, most introduce operator concepts in an ad hoc manner, and few discuss the subject within the general framework of operator theory. This is in contrast to quantum theory, where the use of operators and concepts from functional analysis is common. However, casting electromagnetic problems in terms of operator theory produces useful insights into the mathematical properties and physical characteristics of solutions. For instance, the commonly used modal expansion of fields in waveguides are immediately justified upon identifying the differential operators as being of the appropriate Sturm-Liouville type. As another example, existence, uniqueness and solvability of integral formulations can often be settled by appealing to the theory of Fredholm operators. Many other examples that illustrate the value of abstracting problems to an operator level are provided. Although the book focuses on mathematical fundamentals, it is written from the perspective of engineers and applied scientists working in electromagnetics. The book begins with a review of electromagnetic theory, including a discussion of singular integral operators commonly encountered in applications. It then turns to a self-contained introduction to operator theory, including basic functional analysis, linear operators, Green¿s functions and Green¿s operators, spectral theory, and Sturm-Liouville operators. The discussion is at an introductory mathematical level, presenting definitions and theorems, as well as proofs of the theorems when these are particularly simple or enlightening. The tools developed in this first part of the book are then applied to problems in classical electromagnetic theory: boundary-value problems and potential theory, transmission lines, waves in layered media, scattering problems in waveguides, and electromagnetic cavities.
