IEC 62153-4-9:2018

Overview

IEC 62153-4-9:2018 defines a standardized triaxial test method for measuring the coupling attenuation (aC) of screened balanced metallic communication cables. The method uses a concentric outer tube (triaxial set-up) so that results are largely independent of surface irregularities and external electromagnetic fields. The second edition (2018) is a technical revision of the 2008 edition and extends frequency capability and measurement options for modern, highly screened cables.

Key topics and technical requirements

• Purpose: Quantify coupling attenuation (aC) of screened balanced cables to assess EMC performance.
• Test configurations: Two validated procedures:
  • Standard head (standard tube) procedure
  • Open head (open tube) procedure
• Measurement equipment:
  • Use of a balun or a multiport / mixed-mode VNA for differential/single-ended conversions.
  • Specific balun and TP-connecting unit requirements are detailed in the standard (performance characteristics tables).
• Frequency and dynamic range:
  • Applicable from low frequencies up to the limit set by transversal wave propagation in the outer circuit (approximately 4 GHz in theory).
  • Practical upper frequency is limited by the balun when one is used; the 2018 edition explicitly extends the frequency range up to and above 2 GHz.
• Measurement basis:
  • Procedure builds on screening attenuation methods (see IEC 62153-4-4) and uses triaxial geometry to measure transfer impedance, unbalanced attenuation, and coupling attenuation.
• Test reporting:
  • The standard prescribes how to express results and what to include in the test report (sample prep, equipment, test length, plots).

Practical applications and users

Who benefits from IEC 62153-4-9:2018:

• Cable manufacturers validating screen effectiveness for high-speed and shielded pair cables (e.g., Cat 7a, Cat 8.x, twinax).
• EMC test laboratories performing reproducible coupling attenuation measurements with triaxial fixtures.
• Telecom, data center and networking engineers specifying cable screening performance for installations where external EMI could impair differential links.
• Compliance engineers and spec writers who need standardized test data to compare cable designs or to support product claims.

Practical value:

• Enables reliable comparison of shielding performance across cable types.
• Supports design decisions for shielding, connector and balun choices when targeting specific EMC goals.
• Helps verify manufactured cables meet EMC requirements over a wide frequency span.

Related standards

• IEC 62153-4-4 (screening attenuation, triaxial method)
• IEC 62153-4-3 (surface transfer impedance, triaxial method)
• IEC 62153-4-5 (absorbing clamp method)
• IEC TS 62153-4-1 (EMC screening measurements introduction)
• IEC 60050-726 (vocabulary for transmission lines and waveguides)

Keywords: IEC 62153-4-9:2018, coupling attenuation, screened balanced cables, triaxial method, EMC, balun, mixed-mode VNA, standard head, open head, transfer impedance, screening attenuation.