Study And Design Of RF Multi-Function Filters Based On Microstrip Line

In recent decades,the rapid development of wireless communication technology has played an important role in today's society,and miniaturized,high-performance,and highly integrated microwave passive components are of great significance to improve the wireless communication system performance,and are one of the current research hotspots.The multi-function microwave devices are integrated design of several microwave passive components,which can simplify the complexity of the wireless communication system,effectively reduce the size of the system,and meet the needs of miniaturization of the RF front-end.This thesis combines a variety of microwave devices and filters,and proposes several designs of multi-function filters based on microstrip line.The main research contents of this thesis are as follows:Firstly,the thesis introduces the domestic and abroad research background of the multi-function filters,and then introduces the three-port network analysis method,the microwave filter design principle and the microstrip line theory to pave the way for the subsequent design of multi-function filters.Secondly,the thesis proposes the design method of the balun filter,utilizing the field distribution of the open-circuit transmission line and the filtering characteristics of the parallel coupled microstrip line to realize balan filters.Based on this,three types of balun filters have been designed.The results show that these three kinds of balun filters exhibit good frequency selection and balun characteristics,and they are highly integrated,simple in structure and easy to process.Thirdly,the thesis proposes the design method of the filtering power divider,the main design method is to combine a dual-mode resonator with Wilkinson power divider structure.The Wilkinson power divider,parallel three-line and cross-shaped dual-mode resonators have been analyzed.The results show that the filtering power divider has good filtering performance,and at the same time has good power distribution characteristics and good isolation,which satisfies the requirements of multi-function microwave devices.Finally,the thesis proposes a filtering phase shifter design method based on dual-mode resonators.The odd-mode in the dual-mode resonator of the phase-shifted channel leads to the even mode,while,the odd-mode in the dual-mode resonator of the reference channel lags behind.In the even mode,the phase difference of the two output signals is controlled by changing the relative position of the odd and even mode.In this thesis,the odd-even mode analysis method is used to analyze the resonance characteristics and phase characteristics of the dual-mode resonator.Simulated and measured results show that the filtering phase shifter can achieve 180° phase shift within the passband,with high integration,simple structure,and low processing cost.It is a kind of multi-function microwave device with good performance.