This updated and revised 3rd Edition provides an introduction to microwave theory and techniques suitable for use as a textbook by undergraduates or senior technical college students. Recent advances in technology now incorporated into the new edition include microwave circuits and s-parameters, microstrip circuit techniques and microwave monolithic integrated circuit techniques. The contents fall into two main parts. The first consists of a theoretical development of electromagnetic propagation of guided waves starting from Maxwell's equations and the material's properties. It includes a summary of microwave circuit techniques and a discussion of wave propagation in microstrip, rectangular and circular waveguides, conducting media, ferrite media and plasma. The second part consists of a descriptive treatment of microwave active devices, components and measurements. The two halves of the book provide an ideal combination of theory and practice.