When simulate a reflector device excited by a plane wave (e.g., an object detected by a radar), the far field output by CST is transformed from near field. The near field is the TOTAL field of incident and reflected field. Then CST uses this far field to calculate RCS etc. This doesn't seem correct to me, as RCS should be computed by SOLELY by the reflected field. Can anyone explain?

CST Studio Suite ​​​​​​​