Studies On The Design Theory And Application Of Novel Generalized Chebyshev Wideband Filters

With the development of the fifth and sixth generations of mobile communications,the comprehensive theory and design of high-performance wideband microwave filters have very broad theoretical significance and application value.In this thesis,with wideband filter structure and design theory transmission zeros study,on the basis of domestic and international broadband filter research in recent years on the proposed new wideband filter design theory,and it has successfully designed three kinds Highperformance broadband filter with low loss,good rectangular coefficient and compact structure.The paper mainly includes the following three aspects:First,a generalized Chebyshev wideband filter design theory based on odd-even mode analysis is proposed,and a wideband parallel-coupled line filter with circular open-circuited stub designed using this theory.Firstly,the transmission zeros of the filter are obtained through the analysis of the odd and even modes,and the ideal generalized Chebyshev function is constructed;Secondly,by analyzing the ideal system function and the system function obtained by the even-even mode analysis,the nonlinear equation system with the characteristic impedance of each part of the filter as the undetermined coefficient is obtained;Finally,the theory of nonlinear equations programmed complete filter design.The theoretical results,the simulation results,the experimental results agree the validity of the theory,this theory also shows the wideband filter may be applied to design a symmetrical structure.Second,analysis of the proposed generalized Chebyshev transfer matrix based wideband filter design theory,design and application of the theory of wideband parallelcoupled line filter with open-circuited stepped impedance stub.Firstly,calculate the transfer matrix cascade filter system function;Secondly,according to a predetermined position of the transmission zero constructed over the generalized Chebyshev system function;Finally,the principle of the minimal square error is calculated for each programming characteristic impedance filter section,to complete the filter design theory.The simulation and experimental results showed that: obtained good pass band and stop-band of wideband parallel-coupled line filter with open-circuited stepped impedance stub in accordance with this design theory.Third,the proposed a novel compact wideband filter using three-mode dual-ring resonator.Formulae based on even-and odd-mode analysis are derived to analyze the locations of the transmission poles and zeros of the resonator.The filter is successfully realized by full wave EM simulation and fabricated test results show that the filter processing can generate transmission zeros at the position specified with low resistance and high resistance band,In order to achieve a rapid produced in the vicinity of the cutoff frequency attenuation.The filter features very compact size and can be used in many wideband wireless communication systems.