Investigation of AMN Impedance Uncertainty Contribution in Conducted Emission Tests

The conducted emission test is one of the important EMC tests in the frequency range of 10 kHz–30 MHz for commercial and military equipment. AMNs are required in order to perform measurements and AMN impedance contributes to measurement uncertainty to some extent. Although AMN impedance is defined in terms of magnitude and phase and its effects are studied in commercial standards, most standards such as military standards only define the magnitude and give no information about the uncertainty contribution. In this paper, firstly we developed a software solution to calculate the theoretical nominal AMN impedance values for a given AMN circuit and calculated the corresponding uncertainty contribution by using the magnitude and phase information in accordance with CISPR 16-4-2. Following this, we instructively studied a variety of widely used AMN types and performed their uncertainty analysis. Finally, we focused particularly on military tests and the uncertainty contribution of the defined military AMNs to military conducted emission tests where phase information is not defined.