Study On Innovative Balanced Bandpass Filters

Recently,with the continuous development of wireless communication technology,and wireless communication terminals are increasingly high requirements.In terms of wireless communication systems,the filter is a vital RF device.Therefore,,it is very significant to pay more attention on highperformance filters.Balancing circuit is particularly important in the construction of modern communication systems,and the filter is one of the key components of the communication system.In this thesis,the balanced band-pass filter in wireless communication is taken as the research object.Based on QuarterMode and Eighth-Mode Substrate Integrated Waveguide Cavities,two balanced band-pass filters were proposed and designed.The two filters are small in size,and suppression performance under CM operation is also excellent.At the same time,in order to make full use of existing spectrum and infrastructure resources.In order to be able to work in multiple communication bands,One of the effective ways is to research and develop High-performance multi-band microwave filters.A novel balanced dual-band band-pass filter,using coupled stepped-impedance resonators(SIRs),is proposed in this thesis.By controlling the impedance and length ratios of the stepped-impedance resonators,the desired operating frequencies of the two desired pass-bands can be easily obtained.And stepped-impedance resonators(SIRs)overcome the drawbacks of the uniform impedance resonator(UIR),with more design parameters.Then further analyzing the principles of this dual-band filter.Based on the above analysis,a balanced dual-band band-pass filter constructed by quarter-wavelength type coupled SIRs is presented.The filter has a simple structure and a small size.Suppression performance under CM operation is also excellent.