Improved Alternative Method for Fast and Simple Transfer Impedance Measurements

The transfer impedance of coaxial cables has been under investigation for many decades. Since this parameter is highly relevant in electromagnetic compatibility (EMC) many theoretical models and various test procedures exist. The method proposed in this letter employs a direct line injection using the magnitudes and phases of two s-parameter, namely reflection coefficient and forward gain, in order to determine the transfer impedance reliably and swiftly. Extracting the transfer impedance requires little post processing and the test setup consists only of a simple adapter and the cable under test. This method also allows to account for different lengths of cables as will be outlined and does not require any alteration of the cable under test. It may be used for ready-made cables with molded, crimped or soldered connectors as well as for open-ended samples of cables. The method presented here extends the model used and the usable frequency range considerably compared to previous work on this alternative approach.