On dielectric losses at microwaves: Sensitive measurements and results

Two methods of measuring the permittivity and the dielectric losses at microwaves are described. With the first method, which uses a circular E010resonator, a sensitivity could be obtained. The accuracy is rather low (≈ 5 percent). The second method uses a high-quality resonator which resonates at the same frequency in the mode if a sample of the proper dimensions is introduced. This method has a sensitivity and an accuracy < 1 percent. With both methods, measurements can be carried out in a large temperature range. Data on several ferrites and dielectrics show a large increase of ε" with temperature in the range 0-200°C.