This part of IEC 61788 describes measurements of the intrinsic surface impedance (ZS) of HTS films at microwave frequencies by a modified two-resonance mode dielectric resonator method [13, 14]2. The object of measurement is to obtain the temperature dependence of the intrinsic ZS at the resonant frequency f0. The frequency and thickness range and the measurement resolution for the intrinsic ZS of HTS films are as follows: . frequency: up to 40 GHz; . film thickness: greater than 50 nm; . measurement resolution: 0,01 mÙ at 10 GHz. The intrinsic ZS data at the measured frequency, and that scaled to 10 GHz, assuming the f2 rule for the intrinsic surface resistance RS (f 40 GHz) and the f rule for the intrinsic surface reactance XS for comparison, shall be reported.