Overview
IEC 61196-1-128:2025 defines a standardized electrical test method to measure the polarization directivity of radiating (leaky) coaxial communication cables. The measurement is intended to quantify how a radiating cable favors vertical or horizontal polarization - a key parameter for designing and validating MIMO (multiple-input multiple-output) wireless systems that rely on controlled polarization behavior along the cable.
Key topics and requirements
- Definition of polarization directivity: difference in link loss between vertical and horizontal radiation directions (expressed in dB) at a given axial antenna position along the cable.
- Test arrangements: two permitted setups
- Free‑space arrangement (arbitration method): cable elevated on non‑metallic posts (1.5–2 m height), antenna on a trolley moving parallel to the cable; antenna-to-cable horizontal distance ≈ 2 m.
- Ground‑level arrangement: alternate arrangement for field or constrained environments.
- Antenna options: dual‑polarized half‑wavelength dipole, two half‑wavelength dipoles, or a single dipole with specified orientations; when using two dipoles, centre spacing ≥ 1 λ.
- Sample length: test cable length ≥ 10·λ of the measurement frequency, but not shorter than 50 m. Segmented testing of longer cables is allowed.
- Test methods: synchronous and separated methods for both complete and segmented samples (procedures for sample preparation and measurement sequencing).
- Equipment and data: requirements include signal generator, receiver, trolley, antennas, loads, connecting cables/connectors and a data collection/processing system; antenna type and gains must be reported if non‑dipole antennas are used.
- Measurement constraints: no other metallic objects within a 2 m diameter cylinder surrounding the cable/antenna axis; specified antenna orientations for vertical, horizontal and radial measurements.
- Reporting: test report must document test arrangement, equipment, sample preparation, measurement positions, frequencies and calculated polarization directivity results.
Practical applications and users
- Cable manufacturers: validate radiating cable polarization performance for MIMO deployments.
- Test and certification laboratories: perform reproducible measurements to IEC requirements for product qualification and customer claims.
- System integrators and wireless designers: use results to predict polarization behavior in distributed antenna systems (DAS), indoor coverage, tunnels, or transportation corridors.
- Procurement/specification authors: reference IEC 61196‑1‑128 in supplier requirements and acceptance testing for radiating cable installations.
Related standards
- IEC 61196‑1 (generic coaxial cable specification)
- IEC 61196‑1‑127 (electrical test methods - link loss of radiating cable)
- IEC 61196‑4 (sectional specification for radiating cables)
- IEC 60068‑1 (environmental testing guidance)
Keywords: IEC 61196-1-128, radiating cable, polarization directivity, MIMO, coaxial communication cables, test methods, free-space arrangement, dipole antenna, link loss, segmented samples.
Open preview (PDF)Coaxial communication cables - Part 1-128: Electrical test methods - Polarization directivity of radiating cable
