An alternative approach to determination of the S-parameters of noncoaxial devices

Non-coaxial (non-insertable) devices are indispensable by EMC testing. Absorbing clamps belong to them. They are verified with the Vector Network Analyzers (VNA) which unfortunately have coaxial ports. The clamp can be connected to the VNA only if it is embedded in adapters. By verification the clamp must be de-embedded i.e. the contribution of adapters must be extracted from the measured S-parameters. The Thru-Reflect-Line (TRL) calibration of the VNA would be suitable tool for this task, but this function is only optional in the firmwares of the VNAs. In this paper the alternative approach consisted in calibration with the Short-Open-Thru-Match (SOTM), supplemented with the measurements of all S-parameters of the two adapters cascaded face to face is presented. Applicability of the method is verified metrologically.