RESONATORS OF MECHANICALLY TUNABLE WAVEGUIDE FILTERS FOR TROPOSPHERIC COMMUNICATION

The class of resonators which allows building mechanically tunable waveguide bandpass filters with near constant bandwidth in overall a wide tuning frequency range has been investigated. The concept comprising in a successful combining inductive and capacitive discontinuities to obtain near constant quality factor of resonators in wide frequency variation range is implemented. It is proved that the most technologically advanced solution can be obtained by using the waveguide connections containing double ridged sections for compensation of phase shifts in resonators appearing because of frequency variation. Adequatemathematical models of the resonators based on generalized scattering matrix approach are obtained. The diffraction problems for doubled discontinuities, such as doubled ridged sections in rectangular waveguide, have been solved by the integral equation method. The calculation of resonance frequencies and quality factors of resonators are carried out in wide dimension range variations. Due to near constant quality factors over wide tuning frequency range, the developed waveguide resonators open new possibilities in realization of high efficient and cost effective frequency tunable filters of transmit tropospheric stations and various telecommunication systems for tropospheric communication