IEC 62431:2008

Overview

IEC 62431:2008 - Reflectivity of electromagnetic wave absorbers in millimetre wave frequency - Measurement methods - defines standardized measurement procedures for determining the reflectivity of electromagnetic wave absorbers (EMA) in the millimetre‑wave (mmWave) band. The standard covers normal and oblique incidence and measurements for each polarization. It applies across the 30 GHz to 300 GHz frequency range, for reflectivity values from 0 dB to −50 dB, and for incident angles between 0° and 80°. IEC 62431:2008 replaces IEC/PAS 62431 and the bilingual 2011 publication corresponds to the 2008 English edition.

Key Topics and Requirements

• Measurement scope: Normal incidence, oblique incidence and both polarizations in the mmWave range.
• Frequency & range: 30–300 GHz; reflectivity measurement range 0 dB to −50 dB; incident angles 0°–80°.
• Specimen preparation: Requirements for specimen size, reference metal plate, surface roughness, flatness and mounting/holder methods.
• Measurement methods:
  • Horn antenna method (typical far‑field configuration).
  • Dielectric lens antenna methods: focused‑beam and parallel‑beam approaches.
• Instrumentation & calibration:
  • Use of Vector Network Analyzers (VNA) and directional couplers.
  • Calibration procedures (response calibration, isolation calibration, TRL concepts referenced).
  • Dynamic range considerations and methods to enlarge dynamic range and reduce spurious reflections.
• Environmental and procedural controls: Temperature, electromagnetic environment, equipment warm‑up, measurement distances (Fraunhofer region) and test report content.
• Performance and error analysis: Guidance on dynamic range, measurement errors and reference specimen behavior.

Applications

IEC 62431 is used to ensure reliable, repeatable reflectivity data for materials and absorber products in applications such as:

• mmWave radar and sensor development (automotive and industrial radar)
• 5G/FR2 mmWave component and chamber design
• Anechoic chamber absorbers and EMC testing facilities
• Aerospace, defense and satellite payload design where mmWave scattering control is critical
• Material R&D for low‑reflectivity coatings and absorber panels

Who should use this standard

• EMC and antenna test engineers
• Absorber and materials manufacturers
• Test laboratories and certification bodies
• Radar, telecom and automotive mmWave system designers
• Research institutions working on mmWave propagation and material characterization

Related standards

Refer to other IEC/ISO standards and measurement guides covering EMC, antenna measurements, VNA calibration and material test methods for complementary procedures and traceability.

Keywords: IEC 62431, reflectivity measurement, electromagnetic wave absorbers, millimetre wave, mmWave reflectivity, horn antenna, dielectric lens antenna, VNA calibration, absorber testing.