Derivation and Application of Input Adapter Models to Correct Adapter Errors Associated with Voltage Division Factor Measurements

Traditionally, S-parameter measurements of a line impedance stabilization network (LISN) have only been used to calculate the LISN input impedance (ZLISN). In the first article of this three-part series, we presented a method to measure the voltage division factor (VDF) of a LISN using the S-parameters of the LISN. The coaxial-to-mains-power-receptacle input adapter, necessary to measure both ZLISN and VDF, is known to introduce significant errors. The literature shows a wide variety of adapter modeling approaches that have been proposed and studied to correct ZLISN measurements. Our derivation of VDF enables the application of adapter models to correct VDF measurements as well. In this second article, we calculate the errors due to the adapters needed to perform the measurements, present two measurement-based models of the input adapter, and analyze a significant phase-to-amplitude conversion error mechanism. In the third article, we derive complete model equations based on actual, non-ideal instrumentation, then compare errors and uncertainties.