Research On Mutual Coupling Reduction Between Transmission Line And Patch Antenna

In modern communication systems,with the high integration and miniaturization of communication equipment,more elements need to be integrated in a limited space.Thus the space of the internal equipment becomes increasingly compact,which can easily make the mutual coupling and crosstalk in the internal intensified.Coupling can affect the performance of element,resulting in a decrease in the performance of the communication system.Hence,there is a need to suppress the mutual coupling between elements.In view of the above problems,we proposed two effective methods to reduce the mutual coupling between the patch antenna and microstrip transmission line.The main work of this paper is as follows:(1)We designed a vertical defected isolation wall structure(DIWS)to suppress the mutual coupling between the patch antenna and microstrip transmission line.Firstly,we modeled the patch antenna and microstrip transmission line by electromagnetic software HFSS,and analyzed the influence of the distance on mutual coupling degree by the simulation results of HFSS.Then,we designed the DIWS structure,which includes a thin metal with periodically loaded G-shaped etched slots,and two thin FR4 dielectric substrates are set at each side of the thin metal.The simulation results shown that the designed DIWS structure has a band-stop filter characteristic in specific frequency band.Then the designed DIWS structure is used to eliminate the coupling between the patch antenna and microstrip transmission line.And the simulation results shown that the coupling is reduced by 20 d B by loading the designed DIWS structure at the middle of the patch antenna and the microstrip transmission line.Finally,we study the effect of the DIWS structure on the performance of the patch antenna and microstrip transmission line.(2)For the problem that the proposed vertical DIWS structure is not easy to integrate,we proposed another decoupling method: defected microstrip line structure(DMS).In order to further study the mutual coupling between the patch antenna and transmission line and the decoupling function of the DMS structure,the electromagnetic simulation and circuit simulation are combined in the research process.Firstly,we proposed the equivalent circuit model of the coupling patch antenna and transmission line.Then,a new DMS structure is designed based on the working principle of the defected microstrip line structure,and its equivalent circuit model is extracted from the S parameters obtained from HFSS.Finally,the designed DMS structure is applied to the coupling reduction between the patch antenna and microstrip transmission line,and the simulation results shown that the coupling is reduced by 14 d B,the equivalent circuit is also modeled,and the full-wave simulation results are compared with the circuit structure to verify the correctness of the circuit.