Compact Dual-coaxial Multy-cavity Filter

With the rapid development of wireless communication technology,the competition for spectrum resources is getting more and more intense,and the electromagnetic environment is getting more complicated.Filter has the function of frequency selection and filtering,the performance of the filter plays a very important role in protecting the communication channels and improve communication quality,and widely used in satellite,radar,wireless communications and other microwave systems.With the development of miniaturization,low cost and high performance of modern circuit system,more and more researchers pay more attention to high performance filter.Based on the above background,this paper carried out a study of miniaturized coaxial cavity filters,and designed several miniaturized coaxial cavity filter by adopting different structures.This paper first introduces the basic theory of filter.Mainly introduces the basic technical specifications of the filter,two-port network theory,and introduces three kinds of low-pass prototype filter,finally introduces the low pass to high pass,low pass to band pass,low pass to the band-stop filter's frequency transformation theory.Then use the center to load the short-circuit stub half-wavelength resonator to design a miniaturized cavity filter.Two degenerate modes of a half-wavelength resonator are split by adopting a method of loading short-circuited stubs at the center,and two passband filters are design by using two degenerate modes.Using the dual-mode resonator to design the filter,the number of the corresponding resonator can be reducing,thus achieving the goal of miniaturization.Finally,the simulation design was carried out in HFSS software,and it was processed and tested.Secondly,a concentric structure of quarter-wavelength double coaxial SIRs is proposed to design the miniaturized cavity filter.Take full advantage of the features of quarter-wavelength double coaxial SIRs structure smaller size,higher no-load Q value.Based on this,a concentric structure quarter-wavelength double coaxial SIRs resonator is proposed,finally design three miniaturized cavity filters.Finally,two miniaturized cavity filters were designed in the HFSS software based on the resonator.Finally,one of them was processed and tested.Finally,using the quarter-wavelength dual-coaxial SIR,two quarter-wavelength dual-coaxial SIRs are placed in parallel in a single cavity,and the dual-mode performance is analyzed.Finally,a single-cavity model was used to simulate a dual-mode dual-pass cavity filter in HFSS software.