| With the rapid development of railway and highway infrastructure,how to use public mobile network to achieve timely follow-up coverage of railway and highway tunnel signals under construction has become a common concern in the engineering community.Due to the temporary and timely characteristics of the wireless communication requirements of the construction under construction,the required communication antennas should have the properties of compact structure,mobility and good signal coverage.It can be said that the selection of antenna type and the characteristics of radio wave coverage of the tunnel under construction fundamentally determine the quality and reliability of wireless communication.Therefore,it is of great practical significance to study the radio wave coverage characteristics in the tunnel environment and design relevant tunnel communication antennas accordingly.This paper mainly focuses on the analysis of tunnel radio wave coverage characteristics,tunnel communication antenna design and tunnel radio wave propagation.The main contents are as follows:(1)Demand analysis of wireless communication antennas in tunnels under constructionFirstly,the basic theory of radio wave propagation in the tunnel environment is introduced,and then the coverage laws of different polarized waves in the subway tunnel scene are analyzed through specific engineering applications,and the basic requirements for the design of communication antennas for tunnels under construction are summarized,which will provide information for subsequent tunnel construction.It lays the foundation for the subsequent design of tunnel communication antennas under construction.(2)Design of broadband high-gain circularly polarized array antenna based on sequential rotation layoutAiming at the requirement of uniform radio wave coverage in the tunnel construction environment,a broadband circularly polarized antenna based on the loading of rectangular stubs and arc-cut corner parasitic patches is proposed by using the multi-feed point multiunit combination scheme and the support of eigenmode analysis technology.On this basis,the special circular polarization array antenna for tunnel under construction is designed by using sequential rotation technology,compact feed network and rectangular folding and slotting technology to meet the special needs of the tunnel under construction,such as good mobility,high gain and good gain balance.The design process,sample preparation and performance test of the antenna unit,feeding network and array antenna are given in detail.The test results show that the designed circularly polarized array antenna has good performance and good engineering application potential.(3)Research on the radio wave coverage of the tunnel communication antennaThe tunnel environment is modeled and simulated by the radio wave propagation simulation software WinProp,and the radio wave coverage in the tunnel environment is analyzed by loading antenna patterns of different polarizations,and it is verified that the circularly polarized antenna has better coverage.On this basis,the optimization method of the proposed array antenna in long and straight tunnels is studied by changing the crosssection placement to achieve the characteristics of tunnel radio wave coverage,which provides useful guidance for antenna type selection and placement in practical engineering applications.In a word,starting from the demand for complete coverage of radio waves in railway and highway tunnels under construction,and on the basis of analyzing the radio wave propagation characteristics in tunnels,this paper designs a high-gain and well-balanced utility model that meets the coverage of the LTE frequency band(1.71 GHz-2.69 GHz).The circularly polarized array antenna is used,and the effectiveness of the proposed antenna in the tunnel environment is verified by radio wave simulation software,which provides a new solution for tunnel communication under construction and other engineering applications. |
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