Research On Multi-band-notched Ultra-wideband Filters And Antennas Based On Open-load Stub

In recent years,with the application and development of UWB(Ultra-Wide Band,UWB)technology in the communication field,the research of UWB filters and antennas has been one of the hot issues in the field.At present,the typical structure with the notched band performance is always aimed at the particular narrow-band interference sources,t the research of UWB filters and antenna design which can adjust the number and width of notched stop-band is not systematic and deep enough.In the process of exploration of the solution to this problem,the author carried out the following work:Firstly,the research of the filter with a notch band in the entire UWB frequency band is carried out.At start,the odd-even mode analysis is used in the open-stub structure.Then,based on the analysis of resonance condition,the production mechanism of the notch band is discussed.Last,by attaching the open stub structure to the UWB prototype filter,the notched stop-band interval is obtained,and the step impedance transformation structure is further used in expanding the range of notched stop-band,and a design method of the single notch-band microstrip filter with arbitrarily adjustable stopband within the frequency range of UWB is put forward using a simple technique which provides the theory and design foundation for the following research.Secondly,aiming at interference of WLAN and RFID broadband signal,the design research of wide stopband notch filter based on the structure of third-order open stub is carried out.At first,using the of the edge equivalent technology,the second order open stub structure with wide stopband is got on the basis of the first order open stub.Secondly,based on third-order open stub,wide stopband notch structure is designed.Finally,by attaching these structures to the UWB prototype filter,the single notch-band UWB filter with wide stopband is realized.For the wide stopband notch filter with multi-orders stub,the feasibility and effectiveness is experimentally verified.The experimental results show that the designed filter has a 1 GHz notched stopband,and can effectively inhibit the WLAN and RFID interference.The experimental results shows that there is no energy loss with the designed UWB filter,of which the suppression bandwidth is extended,size is reduced and the overall performance is superior to existing high-level single band-notch filters.Thirdly,aiming at various potential interference in UWB band,based on the open stub structure,the design research work of UWB filters with multiple notch bands are carried out.First of all,the filter with double notch bands is designed through two open stub structures.Second,by combining circular resonant structure and double open stub structure,the UWB filter design with three notched stop-band is completed.Finally,the design of five notched band structure is researched using the above design technique,which verifies the effectiveness of producing multiple notched stop-bands through the construction technology of multimode structure and the multimode resonator.This designed filter has five notched stop-bands,and every stop-band is independently adjustable,which can effectively cope with the interference of WLAN,WiMAX,RFID and C or X band.Based on the proposed design theory and methods of multi-band-notched UWB filters,the experimental results shows that the designed multi-band-notched UWB filters meets the demand of applied indexes,and compared with the existing high-level multi-band-notched filters,it produces more Notch stopbands while the volume is decreased.Fourthly,according to the theory of UWB notch antenna design is incomplete and the existing antenna is hard to deal with a variety of potential interference problems in UWB band,drawing on the design idea of multi-notch stop-band filter,the notched structure and analysis method is introduced into the notched band antenna design.First,the basic open stub structure is applied to the single notched band antenna design,and using the resonant condition analysis and stop-band generating mechanism,single notched band and double notched bands UWB antennas with good notched band performance,adjustable notched stop-band frequency and wide adjustable range are obtained.Secondly,the experimental verified results show that the designed antenna can effectively restrain the frequency interference of WLAN frequency and X-band,and preliminary confirmed that the notched band structure can be used in the design of notch antennas.Finally,the multimode open stub notched structure is applied to the base antenna,and the antenna with four notched bands and notch stop-band of 4 GHz is designed,which confirms the notch-band structure and the analysis method of the complex notch-band structure filter can be introduced into the antenna design.Based on the proposed design theory and methods of multi-band-notched UWB antennas,the experimental results shows that the designed multi-band-notched UWB antennas meets the demand of applied indexes,and compared with the existing high-level multi-band-notched antennas,it produces more Notch stopbands and wider bandwidth of the stopband while the volume is decreased.