Means for monitoring the dielectric parameters of liquid media based on quasiperiodic Bragg microwave structures in a coaxial waveguide

Abstract

The main characteristic of the converter element in resonant microwave sensors that determines the sensitivity of the conversion is the quality factor of the resonance line. In structures with periodic inhomogeneity of the classical topology, the quality factor of the circuit at high values of the signal-to-noise ratio may turn out to be low, which entails the emergence of restrictions on the maximum achievable conversion parameters. One of the ways to increase both the Q factor and the modification of other properties of the microwave structure that affect the overall efficiency of the converter element is the use of quasiperiodic elements. The coaxial cable, where the holes in the dielectric act as inhomogeneity, is presented, forming structure with phase shift. Using the method of flow graphs, we obtained the analytical dependence of the reflection coefficient for this structure. The analysis of the frequency response of the microwave reflection coefficient was carried out for different values of the phase shift and the location of the phase shift section along the length of the cable. A numerical and physical experiments were carried out to determine the frequency dependence of the microwave reflection coefficient with a π-phase shift for various values of the automobile fuel permittivity introduced into the cells.