Research on VHF Buried Sensor Using Leaky Coaxial Cable Techniques

To analyze the electrical characters of leaky coaxial cable (LCX) and the coupling characters of buried sensor which consists of two parallel LCX, a kind of LCX that has a zigzag slot external conductor is designed. Based on the theoretical analysis and industry standards of the leaky coaxial cable with the help of Ansoft HFSS, a commercial electromagnetic simulation software, several LCX working in VHF frequency band are introduced and analyzed by LCX wireless sensing techniques. Performance characteristics transmission attenuation, coupling loss and other important electrical characteristics of the cable are analyzed via experimental data, the simulation result indicates that the length and angle of the slot will influence the performance of buried sensor in the VHF band, the longer notch and the greater inclination angle mean higher receiving efficiency. The influence of the structure and dimension parameters on the coupling characteristics is analyzed. The electrical performance parameters of the leaky coaxial cable and its variation regularity are further calculated. The coupling loss in three position models are tested, comparative experiments show that both simulation and measured results are in good agreement and meet the design specifications.