Adapter and method for improving the LISN input impedance measurement accuracy

The Line Impedance Stabilization Network (LISN) is mostly used in electromagnetic compatibility for conducted and radiated radio-frequency emission and susceptibility tests. The input impedance is one of the most important parameters in LISN calibration. To measure the input impedance, an adapter is required to connect the Vector Network Analyzer (VNA) to the Equipment Under Test (EUT) port of the LISN. For test laboratories, it is of best interest to perform this calibration with high accuracy. Until now the impact of the adapter has not been clearly demonstrated theoretically. We present the design of an adapter and its associated modelling, a method for removing its impact from the measurement, the theoretical error on magnitude and phase input impedance.