This presentation covers the principles of measuring high-frequency electrical networks with network analyzers. You will learn what kind of measurements are made with network analyzers, and how they allow you to characterize both linear and nonlinear behavior of your devices. The session starts with RF fundamentals such as transmission lines and the Smith Chart, leading to the concepts of reflection, transmission and S-parameters. The next section covers all the major components in a network analyzer, including the advantages and limitations of different hardware approaches. Error modeling, accuracy enhancement, and various calibration techniques will then be presented. Finally, some typical swept-frequency and swept-power measurements commonly performed on filters and amplifiers will be covered. An advanced-topics section is included as a pointer to more information.