Coupling of very low frequency electromagnetic signals to long man-made conductors
In electromagnetic (EM) methods in exploration geophysics, long conductors are either targets or cultural noise. Throughthe Earth (TTE) radio, which operates on the same physical principles, can be used to study the effects of such objects on EM survey systems. TTE radio signals have been observed to couple to long man-made conductors, such as railway tracks, which greatly increase the signal's lateral range. However, the effect of parameters such as ground conductivity or transmitter/receiver configuration on signal range is poorly understood. We use the finite-difference time-domain (FDTD) method to model TTE radio signals in the presence of long man-made conductors. The use of FDTD for this application is validated with an analytic solution and compared to field data. The successful use of FDTD for forward modelling of coupling with long conductors allows to determine the potential increase of a TTE radio signal's lateral range for a specific mine site. These results are directly applicable to problems such as detecting thin wires in tunnels or improvised explosive devices, or accounting for such conductors as cultural noise.
|Conference||SEG International Exposition and 86th Annual Meeting, SEG 2016|
Ralchenko, M., Roper, M., Svilans, M., & Samson, C. (2016). Coupling of very low frequency electromagnetic signals to long man-made conductors. In SEG Technical Program Expanded Abstracts (pp. 2154–2158). doi:10.1190/segam2016-13688479.1