ABOUT THIS BOOKNo system in science or engineering can be successfully designed, analysed and specified unless it is backed up by precise quantitative measurements. This is particularly difficult in the field of microwaves where, more often than not, the parameter(s) of interest cannot be observed directly but must be inferred from the measurement of other related parameters. Although the advent of the automated network analyser has eliminated much of the previous drudgery, the problems of interpreting the digitally displayed information still remain. One purpose of this book is to provide the reader with a thorough understanding of the microwave circuit model and its limitations, and thus eliminate the many potential pitfalls that otherwise await the unwary experimenter.