Robust SOLT and alternative calibrations for four-sampler vector network analyzers

This paper assesses the accuracy of several proposed lumped-element calibration techniques for four-sampler vector network analyzers in the face of imperfectly defined standards. We find that these methods offer a wide range of accuracies, depending on the standards and how well they can be modeled. We introduce a new robust short-open-load-thru calibration that requires the same measurement and computational effort as traditional methods, but provides much better accuracy in transmission measurements and slightly better accuracy in reflection measurements.