等效电路法研究漏泄同轴电缆传输和耦合特性

研究了以埋地漏泄同轴电缆作为分布式传感器的电气特性,拟应用于隧道、铁路沿线等防止入侵破坏和预警山体塌方信号的探测.以垂直开槽漏缆结构为例,利用HFSS搭建全波仿真模型,理论分析并提取出缝隙的等效电路模型,从而以该模型为基础分析漏缆的传输、反射和耦合特性.从等效电路模型出发,运用ABCD矩阵计算出了等效电路模型中的电路参数值及漏缆间耦合参数值.理论计算与全波仿真非常吻合,验证了等效电路的正确性.结果表明,与HFSS仿真相比,本文提出的等效电路方法占用计算资源较少且大大缩减了仿真时间,解决了HFSS仿真漏缆长度受限及耗时太长的难题;同时理论计算出了等效参数值和漏缆间耦合参数值,更直观反映了漏缆间的耦合特性.

Transmission and coupling characteristics of leaky coaxial cable using the equivalent circuit

We studied the electrical characteristics of the buried leaky coaxial cables(LCX) as a distributed sensor, applying to detect the intrusion signal and the landslides early warning signal in tunnel and railway, etc. Taking the vertical slot structure as an example, we set up a LCX model using HFSS, and then analyzed the theory and extracted the equivalent circuit model. Based on the equivalent model, we analyzed the transmission, reflection and coupling characteristics of the leaky coaxial cable; we also calculated the equivalent parameters and the coupling parameters using the ABCD matrix. The theoretical calculation is very consistent with the full-wave simulation, which proves the equivalent circuit is right. Results show that compared with the HFSS simulation, the equivalent circuit occupies less computing resources and greatly decreases the simulation time, which will solve the problem that the HFSS simulation cable length is limited and time-consuming; we also theoretically calculate the equivalent parameters and the coupling parameters between the LCXs, which show the coupling capability between the LCX directly.