The frequency-domain EM response of a thin vertical tabular conductor in a two-layer earth was obtained by solving the electric field integral equation numerically. The method of point collocation and expansion of the scattering current components in global polynomic basis functions was employed. Selection of polynomials which obey a boundary condition of no current flow from the edges had a beneficial effect on the results. As the number of basis functions increases, the solution converges to a stationary value which is valid over a sufficiently wide range of parameters to permit the computation of horizontal loop (Slingram) profiles over a plate which can be large enough to simulate a semi-infinite half-plane. The solution gradually worsens as the conductivity contrast between the plate and the host increases, and it eventually fails in situations where magnetic induction effects are strong and electric effects are negligible. The solution also worsens as the plate size increases or as the vertical magnetic dipole source approaches the plate.--Modified journal abstract.

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