IEC 63185:2020 pdf download

IEC 63185:2020 pdf download.Measurement of the complex permittivity for low-loss dielectric substrates balanced-type circular disk resonator method
1 Scope
This document relates to a measurement method for complex permittivity of a 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 is taken into account accurately on the basis of the mode-matching analysis.
5 Theory and calculation equations
A resonator structure used in this method is shown in Figure 1. A thin circular conductor disk with radius R is sandwiched between a pair of dielectric plate samples to be measured having the same thickness t and dielectric properties ε r ‘ and tan δ. Dielectric samples are sandwiched by two parallel conductor plates. The thickness of the conductor disk is negligibly thin in the analysis. The resonator is excited and detected by coaxial lines through excitation holes having radius a and length M. Because only the TM 0m0 modes have the electric field in the center of the resonator, only those modes are selectively excited in the resonator, where the electric field components in the resonator are normal to the plate samples for those modes. ε r ’ and tanδ normal to the dielectric plates are determined from the measured values of the resonant frequencies f 0 and the unloaded Q-factor Q u for the TM 0m0 mode by solving the following resonant condition derived from the mode-matching analysis, where the exciting holes are accurately taken into account:
6 Measurement system
Figure 3 shows a schematic diagram of a vector network analyzer measurement system for a transmission-type resonator. A scalar network analyzer can also be used for measuring equipment, because resonant frequencies and Q-factors can be derived from the frequency dependence of the amplitude of the transmission, S 21 . However, a vector network analyzer has an advantage in precision of the measurement. Furthermore, resonant frequencies and Q-factors are more accurate and less susceptible when they are derived from complex values of measured S 21 data by using the circle fitting on the complex plane of S 21 [7].The structure of the resonator used in the complex permittivity measurements is shown in Figure 1. A pair of dielectric plate samples to be measured, thin circular conductor disk, and two parallel conductor plates constitutes a balanced-type circular disk resonator. The resonator is excited by coaxial lines through excitation holes and under-coupled equally to the input and output ports.
7 Measurement procedure
7.1 Preparation of measurement apparatus Set up the measurement equipment and apparatus as shown in Figure 3. The cavity resonator and dielectric samples shall be kept in a clean and dry state, as high humidity degrades unloaded Q-factors. 7.2 Adjustment of measurement conditions Set up the measurement conditions of a vector network analyzer. The interval between discrete frequency points shall preferably be less than one tenth of the half width of the resonant waveform. Intermediate frequency band width (IFBW), like as digital band pass filter condition in vector network analyzer, is determined such that the noise floor is at least 20 dB lower than the peak values. 7.3 Calibration of a vector network analyzer A vector network analyzer shall be calibrated by using calibration kits.