New requirements for EMC testing of telecommunication equipment have been introduced with the publications of CISPR 22 edition 5.0 as EN 55022:2006. Impedance stabilization networks (ISNs) based on previous versions of EN 55022 must be replaced by ISNs with the new LCL values.
LCL stands for longitudinal conversion loss which describes the losses which occur along a telecommunication line where an unwanted conversion of balanced signals into common mode signals takes place. This has a significant influence on the emission of the line. The ISN establishes the common mode termination impedance for the EUT’s telecommunications port during EMC measurement and emulates the unsymmetrical contribution (LCL) of the connected line. Different ISNs are available in relation to the line category, line numbers and pin-arrangement.
ISNs for Cat. 3 and Cat. 5 typically consist of a basic network with LCL adapter sets. The new ISN for Cat.6 requires a different concept because of the higher LCL and increased transmission bandwidth of Cat.6 applications. Fixed RJ45 connectors are used instead of exchangeable LCL adapter sets.
Teseq, formally Schaffner Test Systems has introduced the ISN T8-Cat6 to meet these new requirements and has a complete range of products for CISPR 22/ EN 55022 conducted measurements. Calibration adapter sets (CAS) are available for Teseq’s family of ISNs and an extension of the CAS ISN adapter set is available for the ISN T8-Cat6. It’s measuring parameters are CM impedance, phase angle, voltage division factor, isolation and LCL.