Automatic microwave network measurements

Network measurements using scattering parameters at microwave frequencies date back to before World-War II in different forms. With the advent of sweepers, the first phase of automation was achieved. Errors in reflection and transmission measurements were reduced by means of better hardware design until the next step of automation took place. Digital computers not only increased the speed of measurements, but were capable of correcting vectorial errors. The chronological development of S parameter-measurement techniques and error analysis is discussed.