Investigation of Band-Pass Filters of K-Range on Rectangular Concentric Resonators

Abstract

Introduction. Simple-shaped cavity resonators: rectangular, cylindrical and coaxial, are widely applied in modern microwave engineering in design of different functional devices of middle and high power levels. Parameters of resonators can be obtained analytically by using expressions from literature. Concentric resonators, performed on the basis of classical simple-shaped cavities with a central metallic core represent a new class of electrodynamic systems of microwave range, the properties of which remain poorly studied. One of these structures, named a rectangular concentric resonator (RCR) is proposed in the paper as a basic unit of K-band bandpass filters (18...26 GHz).Aim. To study potential possibilities of RCR for creation electromagnetic signals filtration devices of micro wave range.Materials and methods. The finite element method implemented in the package COMSOL was used to investigate electrodynamic characteristics of RCR and scattering matrix parameters of the microwave filters on RCR basis.Results. Simple polynomial expressions for computation of normalized resonant wavelengths of RCR were obtained at the first stage of modeling. Next, two models of passband microwave filters by RCR with different sizes were built and their EM characteristics were studied. Cavities sizes were determined numerically and practical recommendations on the realization of a new type bandpass microwave filters were formulated.Conclusion. New results of the finite-element analysis of spectral characteristics of two models of bandpass Krange filters on rectangular concentric resonators were represented. The advantages of the filters were indicated. Simple analytical expressions for calculation of the resonance wavelengths of the considered concentric resonators were obtained.