I. Introduction
The appearance, size and posture of a target and many other factors are all able to affect its radar cross section (RCS) values, and the RCS is a key element in the target recognition [1]. To advance electromagnetic scattering theory and applications, many computational electromagnetics approaches about RCS have been developed, and they can be divided into three main categories, namely, exact analytical methods, numerical calculation methods, and high-frequency asymptotic methods [2]. Despite the rapid development of the hardware and software, these approaches usually cost plenty of computational, physical and manpower resources, especially when uncertainties are taken into account [3]– [5].