Research On Microwave Passive Circuit With The Frequency Selectivity

The microwave passive component with frequency selectivity is to integrate the fil-ter and other microwave passive components into one component,which possesses the function of multiple components and can effectively reduce the size of microwave circuit.Thus,it is studied in this thesis including the topics as follows:Firstly,the Wilkinson filtering power divider is studied,and several Wilkinson filter-ing power dividers with different coupling topologies are designed.At first,two kinds of filtering power dividers with different coupling topologies are designed according to dif-ferent cascade modes of filter and power divider.The first kind of filtering power divider is with an asymmetric structure,and uses two resonators to realizes second-order bandpass response and the isolation between output ports within the passband.In order to analyze the designed filtering power divider,the traditional odd- and even-mode analysis method is extended to make it suitable for asymmetric three-port network.The second kind of filtering power dividers use four resonators to achieve second-order bandpass response.The isolation between the output ports can be achieved in a wide frequency range,but its size is large.The reasons for the difference between the performance of different coupling structures are analyzed.Based on this,a filtering power divider is designed with a novel coupling topology which is different from the two coupling topologies mentioned before.It realizes good isolation in a wide frequency range between two output ports,and only occupies three resonators to realize the second-order band-pass response.Therefore,this filtering power divider achieves the balance between performance and size.Secondly,balanced-to-balanced(BTB)Gysel filtering power divider is studied,in-cluding the BTB Gysel filtering power divider with single-passband equal-power out-put,single-passband arbitrary power distribution ratio output and dual-passband equal-power output.Firstly,the BTB Gysel filtering power divider with single-passband and equal-power output is studied.The design method using odd mode resonators coupling to achieve bandpass response and suppress common-mode signal,and using even-mode resonator to produce equivalent magnetic coupling to realize the isolation between two output ports is proposed.Based on this,the design of BTB Gysel filtering power divider with arbitrary power division ratio and single-passband response is studied,and the cor-responding design formulas are given through detailed theoretical deduction.In addition,an equal-power output BTB Gysel filtering power divider with dual-passband response is designed.This filtering power divider realizes dual-passband response,and achieves high isolation and common mode suppression at both passbands.Thirdly,balanced-to-unbalanced(BTUB)Gysel filtering power divider is studied.A Gysel filtering power divider with onw balanced input port and two single-ended output ports is designed.Compared with the reported researches,this filtering power divider can suppress common-mode signals in a wider bandwidth,and has a wider upper stopband and a compacter structure.Fourthly,the crossover with bandpass response is studied,including single-ended filtering crossover and differential filtering crossover.At first,a new method of filtering crossover design using both electric coupling and magnetic coupling is proposed.The isolation between two signal paths in crossover is realized by utilizing the mutual can-cellation between electric coupling and magnetic coupling.Compared with the reported researches,the multi-mode resonator is not used in this design.Therefore,the designed filtering crossover has a compacter structure.Moreover,a differential filtering crossover which can be used in differential circuits is designed for the first time.This filtering crossover achieves good suppression for common mode signals,and high isolation be-tween two differential signal paths.Finally,the rat-race hybrid with bandpass response is studied.A new method of designing filtering hybrid is proposed by using filtering power divider and filtering balun.This method makes the design of filtering hybrid able to refer to a large number of existing researches of filtering power dividers and filtering baluns.So,it greatly simplifies the design of filtering hybrid,and makes the design have great flexibility.In this thesis,the proposed design method has been fully proved in theory.