Fields generated by bare and insulated cables buried in a lossy half-space

The propagation constants and resulting fields for the current excited on bare and insulated cables buried in a lossy Earth medium are examined. The fields are formulated in integral form under the thin-wire approximation. The discrete mode propagation constants for the insulated and bare cable types have dramatically different behavior, and subsequently affect the radiated fields. Unlike the insulated cable, it is shown that for the bare conductor the accurate determination of the propagation constant is imperative in the calculation of some of the field quantities at the Earth´s surface. Simple near-field expressions are developed from the integral forms and numerical results are presented for various cable structures and burial depths. The study implies that the use of various commonly utilized approximations, such as the uniform axial current assumption, may not be valid for the bare or grounded buried conductors