V.V. Komarov – Dr.Sc. (Eng.), Professor, 

Department «Radio Electronics and Telecommunication», Yuri Gagarin State Technical University (Saratov) 

Е-mail: vyacheslav.komarov@gmail.com

A.I. Korchagin – Ph.D. (Eng.), Deputy Director for Research, 

Mitishinskiy SPI Radio-Measuring Instruments (Mytischi town, Moscow region)  

Е-mail: korchagin@mniirip.ru

V.P. Meschanov – Honored Scientist of RF, Dr.Sc. (Eng.), Professor, 

Director of NIKA-Microwave, Ltd (Saratov)

Е-mail: nika373@bk.ru

Microwave cavity resonators find wide practical application nowadays to design different functional devices including filters. Resonators on cavities of simple configuration (usually rectangular or cylindrical) with metallic various shaped inserts allow reducing sizes of microwave devices what can be useful for aerospace applications. One of such cavities, namely modified reentrant cavity (MRC), has been proposed in the present study as a basic unit of bandpass filter of C-band (4...8 GHz). Eigen electromagnetic (EM) characteristics of MRC: the resonant wavelengths and the unloaded Q-factors have been simulated by using the finite element method (FEM) implemented in commercial software COMSOL V.5.2 in a wide range of sizes variation. Numerical analysis has shown that MRC has reduced sizes at fixed frequency in comparison with not only classical cylindrical cavity but even conventional reentrant cavity widely used in klystrons design. Moreover it demonstrates high values of the Q-factor what is important for filters. New design of microwave bandpass filter on MRC has been proposed and simulated numerically. Filter is made of two identical MRC linked by the coupling circular aperture made in metallic wall between cavities. The inner conductors of the standard 50-Ω coaxial feed lines are connected with metallic inserts by metal rods while another rod connects bottom and upper walls of the filter passing though the circular aperture mentioned above. The 3D FEM model has been built to simulate this microwave two-port network. The filter made of Aluminum is designed at the central frequency 5,96 GHz, and the fractional bandwidth is 2,4%. The simulated insertion loss is less than 0,03 dB. Maximum sizes of this device: a = 20 mm, h = 41 mm, where a  is the diameter, h is the height. Return loss at the central frequency is 27 dB. Obtained numerical data can be used to design not only filters but different microwave devices on MRC.

Komarov V.V., Korchagin A.I., Meschanov V.P. Electrodynamic modeling of microwave resonator filter. Radiotekhnika. 2020. V. 84. № 7(14). P. 20−25. DOI: 10.18127/j00338486-202007(14)-03.

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