An Error Correction Procedure for Multi-Port Measurements at High Frequencies

Abstract. The multi-port method for the measurement of the scattering parameters of multi-ports with the help of a vector network analyzer (VNA) with only two measurement ports is presented. For the measurements only two ports of the N-port device can be connected to the two ports of the VNA at a time. The remaining N-2 ports of the device under test (DUT) are connected to external terminations. As these external terminations might be mismatched, the measured scattering parameters depend on the reflective characteristics of the terminations. An error correction becomes necessary in order to calculate the effective scattering parameters of the DUT (Tippet and Speciale, 1982; Lu and Chu, 2003).
In contrast to the correction method of Tippet and Speciale (1982), the multi-port method has the advantage, that the external terminations can be chosen arbitrarily. Thus, a realization as an open or short circuit is possible as well. Furthermore, the terminations can be unknown except for one, similar to self-calibration procedures of VNAs. This helps to improve the accuracy of the measurements, because the inconsistency problem due to a slightly erroneous knowledge of the frequency characteristics of the terminations can be eliminated.