Research On Filtering Antenna Technology Based On Independent Controllable Radiation Nulls

As an indispensable RF front-end for transmitting or receiving signals in communication systems,antennas carry the important mission of efficient,accurate and agile transmission of information in the 5G era with rapid growth of mobile data.However,with the increasing number of RF devices in multi-band different standard communication systems,the caliber area of the antenna is limited more and more,and the complex communication environment causes increasingly serious interference to the transmission of information in different frequency bands.Therefore,the contradiction between the urgent demand of high-speed and high-quality communication and the serious lack of system resources is becoming more and more prominent and becoming a hot spot and a difficult problem to be solved by the current RF frontier technology.In order to solve the above highlighted contradictions and difficulties,this paper addresses the thought and method of filtering antenna integration design.That is,the antenna and filter set into a comprehensive filtering antenna(FA)embedded module,further development of microwave passive components and antenna integration miniaturization integrated design and application research.Through the research on new concept technology of microwave filtering antenna,the research and development goal of high speed and high-quality dexterous communication system gradually iterated to achieve.In this paper,the new concept technology of filtering antenna is thoroughly investigated and analyzed,the topology and design method of filtering antenna based on independent controllable radiation nulls is creatively proposed.The typical optimized dimensions and performance indexes of this filtering antenna are presented,and the experimental verification is completed to prove the correctness,effectiveness and practicality of the design method.The main research and innovation elements of this thesis are as follows:1.The design method and topology of the compact filtering patch antenna with independent controllable radiation nulls of double split slot structure are proposed and established to realize the filtering antenna with independent adjustable and controllable double nulls.The radiation principle of microstrip patch antenna is investigated,with the extraction of poles technique,the microstrip filtering antenna structure is formed by fusing the split shape slot of double band resonance structure on the patch surface.Without the additional filtering circuit structure,the design requirement of miniaturization is realized.The LC equivalent circuit model is employed to analyze the resonance characteristics of the band-stop structure,and the independent control of the radiation nulls is accomplished by adjusting the resonance frequency.Compared with other microstrip filtering antennas,the structure has the advantages of compactness and excellent outof-band rejection characteristics,and the feasibility of the structure and the correctness of the design method are verified by experiments.2.The design method and topology of the resonant and coupled dual structure radiation nulls independent controllable broadband filtering patch antenna are proposed and established.The design bandwidth of the filtering antenna is significantly improved,achieving the unique performance of independently adjustable and controllable double nulls.Firstly,the F-feed structure is proposed to optimize the characteristic impedance of the microstrip antenna,which makes the bandwidth of the antenna doubled,breaking through the traditional microstrip antenna with low transmission characteristic impedance between the two radiation slits leads to narrow antenna bandwidth.The pole and cross-coupling multiplexing technique is used to introduce resonant band resistance structure,multi-path source and load coupling structure to form a dual structure characteristic to obtain the out-of-band radiation nulls.By analyzing the resonance characteristics of the equivalent circuit and adjusting the cross-coupling level,the radiation nulls can be adjusted and controlled independently.A microstrip patch filtering antenna with wide bandwidth,miniaturization and high out-of-band rejection level is fabricated,and the feasibility of the structure and the correctness of the design method are verified by experiments.3.The design method and topology of SIW back-cavity filtering antenna with independent controllable radiation nulls of dual-cavity structure is proposed and established,and the three nulls independently adjustable and controllable filtering antenna is realized.The single-layer SIW dualcavity structure back-cavity filtering antenna is proposed,and the multimode characteristics of the dual-cavity extend the impedance bandwidth.Meanwhile,the radiation null is constructed by cross-coupling between the dual cavities.The combined technique of pole and current analysis,the resonant band-stop structure,and the different modes of excitation SIW are applied to optimize the passband selectivity,resulting in a wider range of stopband rejection.By adjusting the resonance mode and cross-coupling level to achieve independent control of the radiation null individually.A broadband SIW filtering antenna with wide rejection and miniaturization is developed and implemented,and the feasibility of the structure and the correctness of the design method are verified by experiments.