Network Analyzer Calibrations - Yesterday, Today and Tomorrow

From the very beginning, network analyzers were calibrated manually. Grease pencils were used to mark the reference level on a CRT display or meter display. Such calibration methods were able to remove some of the measurement scalar errors. Full real time vector error correction wasn´t possible until the introduction of the hp8540A automatic vector network analyzer. It also allowed imperfect standards, i.e. an open, to be defined by a device model. The short-open-load-through calibration method was fully enabled. Since then, a surge in research on vna calibration methods brought us the through-reflect-line family of calibrations. Electronic calibration was invented to simplify calibration. Multi-port, differential and non-linear calibration methods and standards are the current and future challenges.