A total- and scattered-field decomposition (TSFD) technique for the finite-element time-domain (FETD) method is described. This formulation leads to both a volumetric excitation method and a Huygens' surface excitation method to impress the incident field in the total-field region. Leakage suppression into the scattered-field region on the order of -250 dB has been obtained, independent of the mesh density and the propagation angle. In addition, in a free-space environment, the relative error between the calculated total field and the discrete incident field is also on the order of -250 dB for the volumetric excitation scheme. Consequently, this total-and scattered-field approach can provide accuracy that is comparable to a pure scattered-field formulation. Both free space and air-earth interfaces are considered.