The impetuous development of technical opportunities of personal computers (PC) over the last twenty years, and a powerful set of numerical methods available in the arsenal of investigators, have forced the working-out of analytical solutions to radiophysical problems. However, at present the fact is evident that optimal use of computer calculations should be based on the application of analytical methods of boundary problem solutions. These methods allow to increase PC-use efficiency and also expand their calculation abilities to solve complex electrodynamic problems. Hence the authors experience in the development of analytical methods to solve the problems of diffraction of waveguide electromagnetic waves on slot coupling holes, represented in this book, will be useful for investigators interested both in the field of theoretical electrodynamics and in the field of practical analysis of multi-functional waveguide devices and systems with slot coupling elements.