This part of IEC 61338 describes the measurement method of dielectric properties for dielectric resonator materials at millimetre-wave frequency. This standard consists of two measurement methods: a) the dielectric rod resonator method excited by NRD-guide (Non-Radiative Dielectric waveguide) and b) the cut-off waveguide method excited by coaxial cables with small loops. a) The dielectric rod resonator method excited by NRD-guide is similar to the dielectric rod resonator method given in IEC 61338-1-3. This method has the following characteristics: – a complete and exact mathematical solution of complex permittivity is given by computer software; – the measurement error is less than 0,3 % for ε′ and less than 0,05 ×10–4 for tan δ; – the applicable measuring ranges of complex permittivity for this method are as follows: frequency: 30 GHz < f < 100 GHz; relative permittivity: 2 < ε′ < 30; loss factor: 10–6 < tan δ < 10–2. b) The cut-off waveguide method excited by coaxial cables with small loops uses a dielectric plate sample placed in a circular cylinder of the TE011 mode. This method has the following characteristics: – fringe effect is corrected using the correction charts on the basis of rigorous analysis; – the measurement error is less than 0,5 % for ε ' and less than 0,05 ×10–4 for tan δ; – the TCF is measured with high accuracy; – the applicable measuring ranges of dielectric properties for this method are as follows: frequency: 30 GHz < f < 100 GHz; relative permittivity: 2 < ε′ < 30; loss factor: 10–6 < tan δ < 10–2.