Accurate plane-wave excitation in the FDTD method
Different techniques are developed to implement plane-wave excitation on the finite-difference time-domain (FDTD) method, such as the initial-condition, the hard-source, and the connecting-condition techniques, for the total-field/scattered field (TF/SF) formulation. In the TF/SF formulation, the incident field is computed and fed to the 3D FDTD grid on the boundary separating the total-field and the scattered-field regions. Since the incedent field is a known quantity, a closed-form expression can be evaluated on every point of this boundary. A more efficient way of computing the incedent field is by using an incedent-field array (IFA), which is a 1D FDTD grid set-up to numerically propagate the incedent field into the 3D FDTD.