Analysis of arbitrarily shaped three-dimensional (3D) objects in a multilayered medium using the method of moments (MoM) requires the computation of the Green's functions. When MoM is applied in the spatial domain, a 3D integral (one for the Sommerfeld integral, the other two for the integral over the source triangle) should be evaluated. The evaluation of the Sommerfeld integrals is a time-consuming process. A commonly encountered solution for this problem is to perform interpolations using preestablished look-up tables. Here, a general 3D interpolation model has been developed. The interpolation scheme is to select M vertical planes (perpendicular to the interfaces of the multilayered medium) to be tabulated in an overlapping manner to interpolate between them. In this scheme, all the grid values on the same vertical plane are tabulated and a single subroutine call is required to evaluate the Green's function. The interpolation model has been employed to calculate the current distributions on a TE01delta-mode dielectric resonator excited with a microstrip line.