by Brian Walker
Calibration methodology for Vector Network Analysis has evolved over the years. The first calibrations were simple normalizations. Later, with a better understanding of the systematic errors a calibration methodology involving the measurements of three known artifacts was developed to solve for these errors and mostly eliminate them from the measurement. The three calibration artifacts are normally a characterized Open, Short and Load. Theoretically any three artifacts with reflection coefficients widely separated on the Smith Chart could be used but these three are common. Later, as measurements were made at higher frequencies on wafer probe stations a new method, TRL was developed which was more suitable for the application and this article will describe the advantages.
