I. Introduction
The radar cross section (RCS) is the most critical concept in radar detection technology, and it is one of the foundations of radars detection system, which characterizes the physical quantity of the echo intensity generated by the target under radar wave illumination. The RCS of an object is the cross-sectional area of a perfectly reflecting sphere that would produce the same strength reflection as would the object in question. (Bigger sizes of this imaginary sphere would produce stronger reflections.) Thus, RCS is an abstraction [1].