Pratsiuk B. The microwave filters based on composite dielectric resonators

Ph.D. thesis is devoted to investigation of the influence of geometrical and electrophysical parameters of composite dielectric resonators (CDR) on its resonant frequency, its quality factor and coupling coefficient between resonator and rectangular waveguides. The design principles of microwave filters based on CDR are proposed. The electromagnetic field problem of resonance frequencies determination for the different CDR geometries with the help of FEM is solved. The results of verification with experimental data and rigorous analytical equation for sphere resonator are performed. The method of coupling coefficient calculation between CDR and a rectangular waveguide, based on the approximation of the scattering matrix calculated by FEM is elaborated. Knowledge about those coefficients is necessary for tunable filter design at the development stage of selective transmitter-receiver of microwave circuits. The method of compensation of detuning response of tunable filter based on CDR, by choosing the parameters of the resonator, the change of the mutual distances between the resonators and waveguide's metal wall tuning technique are developed. The filters constructed on the base of the СDR have wider bandwidth than the filters based on the DR with the same number of resonators. Application of СDR instead of solid-DR can reduce the number of resonators required for a multiresonator filter with a given frequency band. The high-Q tunable filters based on CDR with micro-electromechanical tuning (piezoelectric actuator and MEMS perturber) are proposed.