A Multireflect-Thru Method of Vector Network Analyzer Calibration

We present a new method for two-port vector network analyzer (VNA) calibration, which uses multiple offset-reflect standards and a flush thru connection. Offset-reflect standards consist of sections of the same uniform transmission line with different lengths, which are terminated with the same highly reflective load. The unknown propagation constant of the transmission line and the load reflection coefficient are then determined simultaneously with the VNA calibration coefficients. We compare our method with the multiline thru-reflect-line (TRL) method and show that both methods yield similar results. Our new multireflect-thru method is solely based upon dimensional parameters of the calibration standards. Therefore, like the multiline TRL method, it can be used to establish a traceable VNA calibration. Thus, the multireflect-thru method constitutes an alternative to the multiline TRL calibration in environments in which the use of transmission lines is troublesome, such as in the case of VNAs with very small coaxial and waveguide connectors. The multireflect-thru method is also useful in on-wafer measurements since it allows us to keep a constant distance between the probes, which reduces the impact of crosstalk and speeds up automated testing.