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.