Technical Problems of the Shunt-Type Asymmetric Artificial Network

Theoretical and experimental investigations were carried out on the characteristics of the shunt-type asymmetric artificial network (AAN). The findings are as follows: 1) The theoretical formulas for the differential- and common-mode impedances as well as the longitudinal conversion loss (LCL) were derived for the shunt-type AAN in terms of the AAN circuit parameters. 2) The common-mode disturbance voltage estimated from the measured voltage is not proportional to the actual common-mode current flowing in the network cable of the equipment under test (EUT). 3) For the common-mode EUT, the shunt-type AAN with a low LCL of less than about 42 dB yields incorrect measurement results with an error greater than 0.5 dB. 4). A more crucial problem is that, for the differential-mode EUT, the measured disturbance voltage decreases as the EUT common-mode impedance decreases.