Changes

The first target to be simulated is a small thin metal (PEC) plate of dimensions 0.3λ₀ × 0.3λ₀, where λ₀ is the free space wavelength (Figure 1). The backscatter RCS of this target is computed first using [[EM.Libera]]'s Surface MoM simulation engine and then using [[EM.Tempo]]'s FDTD engine. To calculate the backscatter RCS as a function of elevation angle θ, we ran an angular sweep of θ in both [[EM.Libera]] and [[EM.Tempo]] from θ = 180º (corresponding to a downward, normally incident, plane wave source) to θ = 90° (corresponding to a lateral, horizontally incident, plane wave source) with a step of 5 degrees. Figures 2 and 3 show the simulation results obtained using [[EM.Libera]] and [[EM.Tempo]] and compare them to the results obtained using the finite element method (FEM) given by Ref. [1]. Both theta (TMz) and phi (TEz) polarizations are considered, and the RCS results are plotted in Figures 2 and 3, respectively. Two sets of FDTD data are presented in these figures, one for a planar PEC square of zero thickness and one for a thin metal plate of thickness 0.01λ₀. It can be seen that the infinitesimally thin planar object in FDTD predicts slightly larger RCS than the actual values.