Consideration of error model with cable flexure influences on waveguide vector network analyzers at submillimeter-wave frequency

In microwave and millimeter wave frequency region, systematic error terms, i.e. directivity, matching and tracking, in vector network Analyzer (VNA) can be corrected by a calibration process. However, it is difficult to correct the other random error terms, i.e. connection repeatability and flexure influences of cables attached to test ports, etc. In the waveguide VNA using frequency extension modules, fortunately, it is unnecessary to consider cable flexure influences of test ports in the measurement uncertainty due to no test port cables being used. However, LO and RF cables making connection from frequency extension modules to microwave VNA have a large impact on the uncertainty in the transmission phase measurements. This paper proposes and demonstrates an evaluation technique of cable flexure influences of RF and LO cables in the millimeter and submillimeter wave VNA using frequency extension modules. Then, new VNA error model considering the LO and RF cable flexure influences are discussed.