I.Yu. Bratukhin1

1 SUAI (St. Petersburg, Russia)

Problem statement. Dielectrics include gases, liquids, amorphous substances, and most crystals. The main physical property that unites these different in physical nature substances is their special behavior in an electric field. Under the influence of the electric field in dielectrics there is a displacement of electric charges - polarization and, practically, no displacement of these charges - electrical conductivity. The complex permittivity is an important characteristic that describes the electrical properties of dielectrics. By measuring the parameters of a dielectric, conclusions can be drawn about its composition, physical properties and the conditions in which it is found. The development of new methods of control, to which dielectrometry can be referred, requires new research.

Objective. To propose a technique for constructing an active measurement system based on the Fabry-Perot resonator containing inhomogeneous inclusions, which will allow to provide a unified approach to the study of the dielectric permittivity of inclusions with the required accuracy.

Results. An autogenerator measuring system based on the open Fabry-Perot resonator in the feedback circuit of a solid-state microwave amplifier was developed and applied to measure the dynamics of nonstationary changes in the dielectric permittivity of functional materials.

Practical significance. The influence of the size and position of the cuvette with the substance under study in the volume of the quasi-optical resonator on the characteristics of the measuring resonator was studied. A cuvette for filling with a powder-like substance. Mathematical modeling was performed to optimize the parameters of the open resonator with a cuvette by the criterion of maximum steepness of transformation of dielectric permittivity changes into the change of resonant frequency of the open resonator.

Bratukhin I.Yu. An active system for measuring the complex dielectric permittivity of functional materials based on the Fabry-Perot resonator. Radiotekhnika. 2023. V. 87. № 6. P. 50−61. DOI: https://doi.org/10.18127/j00338486-202306-06 (In Russian)

1. Vajnshtejn L.A. Otkrytye rezonatory i otkrytye volnovody. M.: Sovetskoe radio. 1966. 475 s. (in Russian).
2. Clarke R.N., Rosenberg C.B. Fabry-Perot and open resonators at microwave and millimetre wave frequencies, 2-300 GHz. J. Phys. E.: Sci. Instrum. 1982. № 15. Р. 9-24.
3. Cullen A.L. Millimeter-Wave Open-Resonator Techniques. Infrared and Millimeter Waves. V. 10. Millimeter Components and Techniques. Part II. Academic Press, INC. Ed. by K.J. Button. 1983. Р. 233-281.
4. Ajmera R.K., Bjeechelor D.B., Modi D.K., Lashinski G. Izmerenija na SVCh s pomoshh'ju aktivnyh system. TIIJeR. № 1. 1974. S. 144-155 (in Russian).
5. Litvinenko O.N. Osnovy radiooptiki. Kiev: Tehnіka. 1974. 208 s. (in Russian).
6. Androsov V.P., Veliev Je.I., Vertij A.A. Poljarizacionnye i spektral'nye harakteristiki otkrytyh rezonatorov s vnutrennimi neodnorodnostjami. Izvestija vuzov. Ser. Radiofizika. 1982. T. 25. № 3. S. 318-328 (in Russian).
7. Gubin A.I., Barannik A.A., Cherpak N.T., Protsenko I.A., Pud S., Offenhäusser A., Vitusevich S.A. Whispering-Gallery-Mode Resonator Technique with Microfluidic Channel for Permittivity Measurement of Liquids. IEEE Trans. on MW Theory and Tech. 2015. V. 63. № 6. P. 2003-2009.