ANSI/SCTE 48-1 2021

Test Method for Measuring Shielding Effectiveness of Passive and Active Devices Using a GTEM Cell

Executive Summary

The shielding attributes of components in a CATV system are critical to system performance. Ingress and egress issues can have detrimental effects on the overall performance of the system from both regulatory and quality perspectives. Ingress issues can cause problems with television picture quality, and the effective transfer of data by allowing spurious signal into the system.

It is the goal of this document to address the passive and active devices in the system and how to properly gauge their performance in this critical area.

Scope

The purpose of this test is to determine the shielding effectiveness against Electromagnetic Interference (EMI) of components. This method subjects the component to an electric field of known strength. There are two individual test methods contained therein. The following depicts the type of device each of the methods are intended.

Test Method #1 – Active / Passive Components – where GTEM cell qualification requirements are met, per Appendix B

Test Method #2 – Active / Passive Components – where GTEM cell qualification requirements are not met, per Appendix B, and field strength probe measurements are taken for each frequency in the test.

This procedure exists in order to provide a standard method of testing between laboratories performing Shielding Effectiveness tests. When utilized this procedure helps to ensure confidence in results when published.

Intended Audience

The intended audience contains both system operators and RF equipment manufacturers.

Areas for Further Investigation or to be Added in Future Versions

Future revisions of this document may build upon the work started here by increasing the understanding of:

  • Variability of data between GTEM Cell systems with varied “uniform field” sizes.
  • The effects of location differences between bare wire and shielded samples within the GTEM cell