Subsurface Electromagnetic Fields of a Grounded Cable of Finite Length

The subsurface fields of a finite line source or current-carrying cable are examined. Some special cases, such as the low-frequency limit, are treated analytically, and some simple working formulas are obtained. The general field expressions are reduced to single integrals with finite limits that are evaluated numerically. It is shown that if the source cable is sufficiently long, the fields are approximated by those for an infinite cable. The results have possible application to downlink communication and radio location of trapped miners.