Validity of the thin-wire approximation for conductors near a material half-space

Numerical results concerning the validity of the thin-wire approximation for conductors near a material half-space are presented. The propagation constants and associated current distributions for the discrete characteristic modes supported by cylindrical conductors located near a lossy planar interface are determined. An axially directed current is still assumed, but an arbitrary azimuthal distribution is taken into account in the formulation. The effect of the lossy interface is incorporated in the Green´s function using a Sommerfeld-type integral. The thin-wire approximation is shown to be acceptable for calculating the fields even when Delta /a<1 as long as the observation point is not directly under the conductor.<>