Influence analysis in the permittivity measurement of the curved materials

In this paper, an open resonator for permittivity measurement of curved materials is proposed. The resonator consists of the cylindrical cavity and the X-band point-focusing antenna, and the energy in the cavity is coupled into the antenna by hole coupling and then radiated into the free space. When the sample is placed in front of the antenna, the reflection coefficient of the antenna is affected, which in turn causes the resonant mode in the cavity to be perturbed, and the change of its resonant frequency and quality factor depends on the complex permittivity of the material. The variation of measurement results under the effect of different factors is analyzed by measuring samples with different curvatures and thicknesses. The results of the permittivity distribution measurement of the samples show that the method can effectively perform permittivity measurement of curved materials with an error of 10% or less under most measurement conditions, also data fluctuations in a few cases.