This text provides a comprehensive and detailed tutorial and reference on microwave sensors, from physical principle through to technology and applications. Microwave sensors were initially developed for military applications. Today they are being widely introduced in civil applications, capitalizing on past experience and the availability of reliable, cost-effective components and sub-systems developed for the telecommunications industry. Microwave sensors have many advantages, including: flexibility and wide range of applications; contactless measurement; wide frequency generation; quick response and minimal effect on the surround. The book should be useful both to engineers and students near to the field and experienced microwave engineers requiring a broader perspective on microwave applications.