In this paper, we determine in a closed form the current distribution in a
thin two-layer tubular conductor with a sinusoidal current in the presence
of a filament with an equal but opposite current. The method of treating the
problem consists in solving an integral equation for the current density in
one layer which enables to find the current density in the other layer by
imposing equality of the tangential components of the electric fields at the
layer interface. An important factor, the AC to DC resistance ratio for the
conductor is also found in a closed form. Some numerical examples, for
current distribution and resistance ratio, versus frequency or geometry
parameters, are presented.
