Impedance stabilization networks (ISN, or with CISPR 16-1-2 called AAN: asymmetric artificial network or AN: artificial networks for coaxial and other screened cables) are defined for measuring of conducted common mode disturbances at information technology equipment (ITE) as required in CISPR 22. The ISN is placed between the equipment under test (EUT) and auxiliary equipment (AE) or load which are necessary for the operation of the EUT. The ISN establishes the common-mode termination impedance for the EUT’s telecommunications port during measurement.
ISN S501A, ISN S502A, ISN S751 and ISN S752 are designed for measurements on coaxial telecommunication lines. The used internal cable has a impedance of 50 Ω for ISN S501A and ISN S502A or 75 Ω for ISN S751 and ISN S752. The cable screen is connected on the AE side to the ground. ISN S502A and ISN S752 are supplied with double screened coaxial cables and N connector. A design example is given in figure D.9 CISPR 22 (EN 55022) and figure G.9 CISPR 32 (EN 55032).