The design of a six-port reflectometer with frequency-independent calibration procedure

The accuracy in the measurement of an unknown reflection coefficient using a six-port automatic network analyzer (ANA) depends in part on the stability of the calibration constants of the system. A six-port reflectometer whose configuration minimizes the variations of these parameters with frequency is described. The advantages of a six-port configuration include a weakly and slowly frequency-dependent calibration process. Consequently, uncertainties due to the variations of the six-port parameters with RF-source stability are reduced. There is no need for a synthesized source, and the number of calibration points can be reduced while the symmetrical distribution of the q_i points can be kept over the whole frequency range.