Useful Analytical Formulae for Near-Field Monostatic Radar Cross Section Under the Physical Optics: Far-Field Criterion

Radar cross section (RCS) is usually defined in the far-field zone. In this case, RCS is independent of the range of the radar from the object. However, in several scenarios, like for military applications or measurements led in anechoic chambers, the object is located in the near-field zone. From the physical optics (PO) approximation and from some simplifying assumptions, this paper presents useful analytical formulae of the monostatic RCS of canonical shape perfectly-conducting objects at oblique incidence angles. The formulae are then compared with the PO integral, which requires two-fold numerical integrations. Finally, the authors also examine the far-field criterion using the resulting expressions.