The IET has organised training courses on microwave measurements since 1983, at which experts have lectured on modern developments. The purpose of this third edition of the lecture notes is to bring the latest techniques in microwave measurements to a wider audience. The book includes a survey of the theory of current microwave circuits as well as a description of the techniques for the measurement of power, spectrum, attenaution, circuit parameters, and noise, measurements of antenna characteristics, free fields, modulation and dielectric parameters. The emphasis throughout is on good measurement practice. All the essential theory is given and a previous knowledge of the subject is not assumed. The book will be of interest to those engaged in the design of microwave measurement systems in both research and industry, those providing microwave measurement systems in both research and industry, in measurement services and those involved in teaching microwave measurements in universities.