| With the adventure of the mobile Internet era,wireless mobile communication network has become one of the most important infrastructures for social development.The public's demand for mobile communication is growing,and the requirements for speed and quality are getting higher and higher.After the scaled application of the fourth generation of mobile communications(4G),the fifth generation of mobile communications(5G)has become the focus of new technology competition in the global mobile communications field.In addition,a variety of broadband wireless access technologies are maturing.Many wireless technologies are being updated.Internet of Things technology is rapidly developing.Wireless mobile communication enters a new stage of social development and integration.All of the above phenomena indicate that 5G,Internet of Things,cognitive radio,full-duplex communication systems,and frequency hopping communication systems are increasingly adoped in civil and military applications.The data volume of these systems is growing at an extremely fast rate,so the demand for bandwidth is rapidly expanding.However,in order to utilize limited spectrum resources more efficiently,we must establish more channels in a limited band.At the same time,higher requirements are required for frequency selectivity and interference rejection.The filter can be an important device in a wireless communication system,and can effectively suppress unwanted signals while allowing useful signals to pass.This thesis mainly studies high-performance band-stop single-ended filter,differential band-pass filter and filter integrated differential power divider.In addition,the SIW-based broadband circularly polarized array antenna is also studied.The main contributions of this thesis are as follows:(1)A new high-performance planar band-stop filter is proposed.In order to improve the performance of the band-stop filter and maintain a simple circuit structure,a three-step impedance converter and two steped impedances are used to compose the band-stop filter.The band-stop filter can achieve good stopband attenuation while maintaining a wide upper passband.The design theory and optimization method of improving the passband on the band-stop filter are proposed.The improvement mechanism and design flow of the circuit are analyzed in details,and the simulation and experimental verification are carried out.This part of work is published in AIP Advances.(2)A novel planar high-performance miniaturized band-stop filter is realized by a symmetrical four-section coupled-line structure.This band-stop filter has wide upper passband bandwidth,lower level of passband reflection loss,high selectivity,and flat passband group delay.The corresponding design theory of the proposed band-stop filter is analyzed.The prediction results were rigorously verified by simulation and experimentation.This part of work is published in Microwave and Optical Technology Letters.(3)Three differential bandpass filters based on terminated coupled-line are proposed.The performance improvement of passband bandwidth,selectivity,out-of-band suppression and common-mode rejection is studied,and the circuit parameters and filter characteristics are derived.A differential narrowband filter,a differential wideband filter with high out-of-band rejection,and a differential wideband filter with high common-mode rejection are designed and verified by simulation and experiment.(4)A wideband filter integrated differential power divider consisting of coupled lines,short-circuited stubs,and 90-degree impedance converters is proposed.The filter integrated differential power divider is analyzed by the odd-even mode analysis method.The differential mode and common mode input impedance,differential mode transmission zero and common mode rejection characteristics of the filter integrated differential power divider are obtained.Then,the proposed filter integrated differential power divider is simulated and fabricated by full-wave simulation software and printed circuit board technology.From the simulation and measurement results,this filter integrated differential power divider has good differential mode power distribution characteristics,good differential mode filtering characteristics and high common mode rejection performance.(5)An aperture-coupled microstrip patch antenna is proposed based on substrate integrated waveguide(SIW).The influence of the parameters of the patch antenna on the performance of the antenna was simulated.Then,based on the proposed aperture-coupled patch antenna,a sequential-rotation-fed array antenna with improved axial ratio bandwidth and impedance bandwidth is designed.The output port signals of the feed network have equal amplitudes over a wide bandwidth,and the adjacent output ports have a phase difference of 90°.The simulation and measurement results of the wideband 4×4 circularly polarized array antenna verify the feasibility of the array antenna with the effective feed network. |
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