On the Calibration of a Microwave Network Six-Port Reflection Analyzer

An operative calibration method for high-frequency six-port reflectometers (SPRs) is presented. The method is based on a segmentation of the bilinear transformation that represents the measurement system. With the segmentation, a number of intermediate parameters that comprises a multidimensional function are obtained. The function is minimized using a gradient method (modified abrupt steepest descent) and Lagrange multipliers to transform the distance search in a 1-D problem. The method was implemented in a practical SPR, and the results were satisfactory, in accordance with the capabilities of an instrument of this kind.