=== Radar Cross Section of Planar Structures ===
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[[File:PMOM124.png|thumb|Planar Module's Radar Cross Section dialog]]
When a planar structure is excited by a plane wave source, the calculated far field data indeed represent the scattered fields of that planar structure. EM.Cube can also calculate the radar cross section (RCS) of a planar target:
:<math>\sigma_{\theta} = 4\pi r^2 \dfrac{|E_{\theta}^{scat}|^2}{|E^{inc}|^2}, \quad\sigma_{\phi} = 4\pi r^2 \dfrac{|E_{\phi}^{scat}|^2}{|E^{inc}|^2}, \quad\sigma = \sigma_{\theta} + \sigma_{\phi} = 4\pi r^2 \dfrac{|E_{tot}^{scat}|^2}{|E^{inc}|^2} </math><!--[[File:PMOM123.png]]-->
'''Note that in this case the RCS is defined for a finite-sized target in the presence of an infinite background structure.''' The scattered θ and φ components of the far-zone electric field are indeed what you see in the 3D far field visualization of radiation (scattering) patterns. Instead of radiation or scattering patterns, you can instruct EM.Cube to plot 3D visualizations of σ<sub>θ</sub>, σ<sub>φ</sub> and the total RCS. To do so, you must define an RCS observable instead of a radiation pattern. Follow these steps:
At the end of a planar MoM simulation, in the far field section of the Navigation Tree, you will have the θ and φ components of RCS as well as the total radar cross section. You can view a 3D visualization of these quantities by clicking on their entries in the Navigation Tree. The RCS values are expressed in m<sup>2</sup>. The 3D plots are normalized to the maximum RCS value, which is also displayed in the legend box.
[[File:PMOM124.png]] Figure 1: Plana Module's Radar Cross Section dialog. [[File:PMOM125.png|800px]]
Figure 2: An example of the 3D mono-static radar cross section plot of a patch antenna.