prBAS EN IEC 63185:2026

IEC 63185:2025 relates to a measurement method for complex permittivity of dielectric substrates at microwave and millimeter-wave frequencies. This method has been developed to evaluate the dielectric properties of low-loss materials used in microwave and millimeter-wave circuits and devices. It uses higher-order modes of a balanced-type circular disk resonator and provides broadband measurements of dielectric substrates by using one resonator, where the effect of excitation holes and that of fringing fields are taken into account accurately on the basis of the mode-matching analysis. This second edition cancels and replaces the first edition published in 2020. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition: a) the upper limit of the applicable frequency range has been extended from 110 GHz to 170 GHz; b) circular disk resonators used for the measurements now include one with waveguide interfaces; c) in calculating the complex permittivity from the measured resonant properties, the fringing fields are now accurately taken into account based on the mode-matching analysis.