On the derivation of bistatic RCS from monostatic measurements

The factors which govern bistatic scattering are discussed and the relations between bistatic and monostatic scattering are presented in terms of the combined effect of individual scattering centers on the target. The concept of reradiation lobe patterns of the individual scattering centers is used to define the bistatic pattern in terms of the monostatic pattern and the bistatic angle β. Analytical arguments then demonstrate that for small bistatic angles, the bistatic RCS is very closely approximated by the monostatic RCS measured on the bisector of the bistatic angle and measured at a frequency lower than the true frequency by the factor cos β/2. The limitations to this approximation which are based on the angular width of the lobe patterns reradiated from individual scattering centers are noted. The approximation is of particular value in translating measured monostatic RCS values into bistatic RCS for small bistatic angles.