IEC 61788-15:2026

Overview

IEC 61788-15:2026 is an international standard developed by the International Electrotechnical Commission (IEC), detailing methods for measuring the intrinsic surface impedance (Zs) of high-temperature superconductor (HTS) films at microwave frequencies. Targeted at professionals in superconductivity, microelectronics, and microwave engineering, this standard specifies procedures using a modified two-resonance mode dielectric resonator technique to assess the temperature dependence of the intrinsic surface impedance at the resonant frequency, f₀.

The standard supports measurements at frequencies up to 40 GHz, for film thicknesses greater than 50 nm, and provides a high measurement resolution (as fine as 0.01 mΩ at 10 GHz). Clear guidance is given on reporting results both at the measured frequency and normalized to 10 GHz, following the established frequency-scaling principles for surface resistance and reactance.

Key Topics

• Intrinsic Surface Impedance Measurement: Focuses on the accurate measurement of Zs in HTS films using dielectric resonators, vital for evaluating microwave losses and performance.
• Measurement Scope:
  • Frequency range: up to 40 GHz.
  • Minimum HTS film thickness: 50 nm.
  • Measurement resolution: 0.01 mΩ at 10 GHz.
• Temperature Dependence: Emphasizes obtaining the temperature profile of Zs, crucial for understanding superconducting film performance in real-world applications.
• Uncertainty Evaluation: This edition introduces an updated approach, replacing "precision and accuracy" with "uncertainty" terminology and providing an informative annex on combined relative standard uncertainty.
• Best Practices for Measurement Configuration: Includes safety and quality considerations for cryogenic and high-frequency measurement environments.

Applications

IEC 61788-15:2026 addresses the needs of industries and research institutions working on:

• HTS-Based Microwave Components: Enabling reliable assessment of thin film superconductors used in resonators, filters, antennas, and delay lines, where low microwave loss and reproducibility are crucial.
• Material Development and Characterization: Supporting advanced R&D in superconducting materials by providing standardized, comparable testing results for surface impedance.
• Quality Assurance: Offering manufacturers and test labs a reference for ensuring products and materials meet stringent international standards regarding the electrical properties of HTS films.
• Interlaboratory Comparability: Results from round robin (comparative) tests are included, fostering international consistency and benchmarking of measurement methods.

Related Standards

For comprehensive superconductivity testing and terminology, the following standards complement IEC 61788-15:2026:

• IEC 60050-815:2024: International Electrotechnical Vocabulary - superconductivity terms and definitions.
• IEC 61788-7: Surface resistance measurement of superconductors using the two-resonator method (for thicker films).
• Other relevant materials and electromagnetic property measurement standards within the IEC 61788 series.

Practical Value

Adhering to IEC 61788-15:2026 ensures:

• Reliable and reproducible microwave surface impedance measurements for HTS films, essential for high-performance electronic and telecommunications applications.
• International harmonization of test methods and data reporting, making it easier to compare results across organizations and borders.
• Enhanced confidence in HTS material properties, supporting faster innovation cycles in next-generation electronic components.

By following this standard, engineers and researchers can ensure their testing methods for superconducting films at microwave frequencies meet globally recognized benchmarks, aiding faster market adoption and improved device performance.