Multiport vector network analyzer calibration using the generalized 3-term error model

•A generalized 3-term error model for the calibration of multiport VNAs is proposed.•The generalized node equation is deduced to solve the actual S-matrix of the DUT.•The fundamental rules of the matrix flow graph are used to calculate the actual S-matrix of the DUT.•Measurements are performed on a four-port device and the results verify the precision of the algorithm.

A generalized 3-term error model, where only three error matrixes are defined, is proposed for the calibration of n-port vector network analyzer (VNA) with n + 1 measurement channels. In this model, the node is replaced by the complex vector, and correspondingly the branch gain is represented by the complex square matrix. According to this error model, which also obeys the fundamental rules of flow graph, the formula for actual scattering matrix of an n-port DUT can be deduced. Finally, the actual S-parameters of a four-port device can be corrected and they are compared with the measurement results by Agilent VNA E5071B. The good agreement attests the precision of the calibration algorithm.