Research On Filtering Antenna Based On Substrate-Integrated-Suspended-Line Platform

The proposal of 5G technology has raised the quality and rate of data transmission in the communication system.At the same time,some problems are introduced to the system which need to be solved.On the one hand,the technology of ultra-dense networks leads to the interference of adjacent bands.Therefore,the extra filter is demanded to suppress the out-of-band noise.On the other hand,the distance is reduced by the technology of Multiple-Input Multiple-Output（MIMO）while the design space is unchanged,and the coupling of elements is getting worse,resulting in distortion of radiation pattern and mismatch of impedance.In view of the above problems,this thesis proposes a design that could integrate filtering response and decoupling function into the antenna.The design is based on the Substrate Integrated Suspended Line（SISL）platform,which has a low-cost and self-package structure.By loading the cavity and parasitic element,the filtering response is realized.On this basis,the isolation of the MIMO antenna is enhanced to further improve the anti-interference ability of the antenna.The main research contents are as follow:Firstly,based on the SISL platform,a low-cost dual-mode antenna with out-of-band suppression is proposed.Taking advantage of the cavity and self-package structure of the SISL platform,a low-cost cavity is formed.Excited by the differentially-fed patch,the cavity works at TE₁₀₂mode.Together with the TM₀₁mode of the patch,the dual-mode performance is achieved.Besides,A radiation null at the upper band is introduced by the cavity,which could suppress the unnecessary noise.The low-cost cavity improves the gain to 10.5 d Bi by reducing dielectric loss.Secondly,based on the SISL platform,a MIMO filtering antenna with enhanced isolation is proposed.The antenna consists of differentially-fed patches,notched stacked patches,and L-shape stripes.The filtering response is realized by utilizing the principle of radiation cancellation,improving the out-of-band suppression to 18.5 d B.Taking advantage of a new coupling path introduced by notched stacked patches,the induced current is eliminated and the isolation is enhanced to 31.3 d B.Therefore,the filtering response and decoupling function are integrated into the proposed antenna.Finally,taking advantage of the SISL structure,the filtering response and decoupling function is integrated into the antenna.A MIMO filtering antenna with enhanced isolation is designed to avoid the influence of out-of-band noise and coupling of elements.The stability of the antenna is improved and the possible drawbacks of 5G technology are avoided.