Cut Microstrip Open Ring Resonator-based Generalized Chebyshev Filter

Because of the controllable finite transmission zeros, high selectivity and planar structure, the General Chebyshev filter based on microstrip open-loop resonator possesses broad application foreground. The thesis is mainly on a method for the General Chebyshev filtering functions synthesis. The main works are described as follows:First, the basic theory of the General Chebyshev filter is introduced systematically. A method of matrix rotation is used to annihilate needless nonzero values in the coupling matrix. Then a filter synthesis program is designed to make the General Chebyshev filter synthesis easy and fast. At last, the independent distribution of the transmission zeros in cascaded matrix and the method to extract the optimum positions of transmission zeros are discussed.Second, the equivalent circuit of the microstrip open-loop resonator is discussed so that we can associate the equivalent circuit method with the soft of high frequency simulation to realize the coupling resonators. Then the relationship between coupling coefficient and coupling distance is discussed as well.Third, a six-degree 2 transmission zeros symmetrical and a seven-degree 3 transmission zeros cascaded bandpassfilters are simulated respectively by using the synthesized coupling matrix, method of matrix rotation and ADS, and simulated results demonstrate the validity and feasibility of the presented theory. On the basis of this experimental research, the main reason for the high insert loss of the microstrip open-loop filter designed in this thesis is analyzed in detail.