Comparison of adapter characterization methods

We review and compare three different methods for characterization of precision adapters. Two of the methods are one-port techniques using two different reflective terminations in the one case and a matched load and multiple lines with reflective terminations in the other. The third technique is a conventional two-port adapter-removal technique. The intrinsic efficiencies of several different adapters are measured with each technique, and the results are compared. The results usually agree within about 0.005 for efficiencies near one. In all cases, the differences are consistent with the estimated uncertainties of the techniques, which range from about 0.002 to about 0.012, depending on the method, connectors, and frequency.