Резонансные спектры неоднородных коаксиальных резонаторов для определения диэлектрической проницаемости жидких сред в СВЧ диапазоне

Abstract

The analysis of the frequency spectrum of the classical homogeneous coaxial resonator with an electrical length of 1/4 of the wavelength and inhomogeneous coaxial resonator lines with different wave resistances. The frequency spectrum of the classical resonator is characterized by low frequency separation of the first and second resonances, so it can be used only in circuits with the study of the amplitude-frequency characteristics for determining the dielectric constant of the medium filling it. A new type of inhomogeneous coaxial resonator lines with different wave resistances is proposed. The frequency spectrum of inhomogeneous resonator is characterized by sharp (up to 4-fold) decrease in the first resonant frequency and a significant (5 fold) increase in separation the first and second ones. Inhomogeneous resonator has 4 times smaller geometric length and can be used in the free oscillation mode of the measuring generator. Inhomogeneous resonator allows the measurement of the dielectric constant of the medium in an extended frequency range from tens of MHz to 1.8 GHz.