| Leaky coaxial cable(LCX for short)has the dual functions of a coaxial cable and a transmitting and receiving antenna.It can propagate wireless signal uniformly and without dead angle and blind area and is widely used in the tunnel environment.Choosing the appropriate hanging height of LCX in the tunnel environment can not only ensure the quality of signal transmission during train operation,but also reduce the maintenance difficulty of LCX.Therefore,it is of great value to study the influence of the hanging height of LCX on the radiation performance of LCX in the tunnel environment.At first,this paper introduces the structure,classification,radiation mode and electrical performance index of LCX.Then LCX model is established and the transmission loss and coupling loss of LCX are simulated and analyzed.Then,On this basis the radiation field of LCX in the circular arch tunnel is calculated based on ray tracing method,and the radiation characteristics of LCX in the tunnel environment are studied.Combined with the actual tunnel environment,the radiation model of LCX in the tunnel is established,the influence of the hanging height of LCX is analyzed by simulating and calculating the coupling loss between LCX and the receiving antenna at different hanging heights of LCX.Then two cases of double-line tunnel and single-line tunnel are studied respectively.The rule that the radiation performance of LCX changes with the hanging height of LCX in the tunnel is obtained by simulating and calculating the radiation model of LCX at different hanging heights.Finally,the experiment is designed based on the experience of tunnel engineering,and the radiation performance of LCX is tested by selecting different hanging height.The test data is compared with the simulation data to verify the accuracy of the simulation analysis.It provides an important reference for the hanging scheme of LCX in practical engineering in the future. |
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