Plane-wave illumination for the TLM method using a partial Huygen´s surface

An efficient solution to the problems associated with plane wave illumination of a scattering body in a TLM mesh, initially presented by Porter and Dawson (see Electronics Letters, p.1683-1884, 1992) is explained. This has applications in determining the effect of electromagnetic interference (EMI) on structures ranging from aircraft to equipment housings. The equivalence of the solution to a partial implementation of the Huygen´s surface (used in the time-domain finite difference (TDFD) method) is outlined. The method allows the use of considerably smaller TLM meshes for problems excited with a plane wave source than previously possible. The method uses the TLM mesh itself to generate the (equivalent of) retarded surface currents for the Huygen´s surface. This gives automatic compensation for any dispersion in the mesh. The method is therefore suitable for problems using a graded mesh without further modification