When the physical structure is illuminated by a plane wave source, the calculated far field data indeed represent the scattered fields. In the context of radar systems, the incident plane wave can be regarded as a transmitted signal to intercept a target. The scattered field can be regarded as the target's echo signal. A target is usually characterized by a quantity called the Radar Cross Section (RCS), which gives a measure of its effective surface area as seen by a radar system.
[[Image:Info_icon.png|40px]] Click here to learn more about the theory of '''[[A Review of Maxwell's EquationsThe_Far-Field_Approximation_for_Radiation_%26_Scattering_Problems#Radar Cross Section Electromagnetic_Scattering_and_Radar_Cross_Section | Radar Cross Section ]]'''.
To compute the RCS of your physical structure, you must define an RCS observable instead of a radiation pattern observable. To do so, follow the steps below: