IEC 61196-1-108:2025

Overview

IEC 61196-1-108:2025 is the 2025 third edition of an IEC standard for coaxial communication cables. It specifies electrical test methods to determine phase, phase constant, phase and group delay, propagation velocity, electrical length, and mean characteristic impedance of coaxial cables used in communications systems. Annex A provides an informative procedure to measure phase dispersion. This edition is a technical revision that replaces the 2011 edition and adds new clauses on sample preparation, test procedure, failure criteria and specification information.

Key topics and requirements

• Scope: Test methods for coaxial communication cables covering phase-related and impedance/velocity parameters.
• Parameters defined: Phase constant (β), phase and group delay, propagation velocity, electrical length and mean characteristic impedance - with relationships and formulas provided for conversions between them.
• Test equipment: Requires a capacitance meter/bridge (per IEC 61196-1-103) and a vector network analyser (VNA) capable of S21 and expanded phase measurements.
• Sample preparation: Two methods:
  • Method 1 (long cables): single sufficiently long cable assembly with connectors.
  • Method 2 (short cables): two assemblies of different lengths (typically one double the other) from the same product - or produce the short sample from the long one after testing.
• Test procedure: VNA-based expanded-phase measurements, calibration procedures and calculation methods for deriving phase constant, phase delay, group delay, propagation velocity, electrical length and characteristic impedance.
• Annex A: Measurement and interpretation of phase dispersion for cables with higher dispersive behavior.
• Quality controls: Clause on failure criterion and clause listing required information to be included in relevant product specifications and test reports.

Applications and users

This standard is practical for:

• Cable manufacturers validating product electrical performance and producing standardized test reports.
• Independent test laboratories performing compliance testing and acceptance checks.
• RF and telecom system integrators assessing cable suitability for high-frequency links (broadcast, mobile backhaul, microwave, satellite and RF test setups).
• Design engineers needing reliable data on delay, velocity and characteristic impedance for system timing, phase-matching and impedance-matching tasks.

Related standards

• IEC 61196-1:2005 - generic specification, definitions and requirements for coaxial communication cables.
• IEC 61196-1-103 - capacitance test methods referenced for sample preparation and impedance calculations.

Keywords: IEC 61196-1-108:2025, coaxial communication cables, phase constant, group delay, propagation velocity, electrical length, characteristic impedance, phase dispersion, VNA, cable testing.