进气道RCS目标特性在整个飞机中占有较大比例,但作为电大尺寸腔体,其RCS特性评估与外机身相比有其固有困难。本文研究了适合于任意腔体RCS评估的迭代物理光学算法,该方法基于磁场积分方程属于高频算法范畴,可以较精确地计算出进气道金属表面电流矢量分布并给出令人满意的RCS结果。通过软件开发实现了任意腔体RCS特性评估,并用标准算例考核了程序准确性。应用该软件对某型心线一定的金属进气道S弯扩压器开展计算研究,获得了不同宽高比扩压器在入射波长为0.03 m下的电磁散射特性变化规律。 Inlet RCS target characteristics account for a large proportion of the entire aircraft, but as a large size cavity, RCS characteristics assessment inherent difficulties compared with the external body. In this paper, an iterative physics optics algorithm suitable for RCS evaluation of arbitrary cavities is studied. The method is based on the field integral equations belonging to the category of high-frequency algorithms, and can accurately calculate the current vector distribution on the metal surface of the intake manifold and give a satisfactory RCS result. Through software development, the RCS characteristic of arbitrary cavity was evaluated, and the standard example was used to evaluate the accuracy of the program. The software was used to calculate the electromagnetic diffusivity of a metal inlet S-diffuser with a certain centerline. The variation of the electromagnetic scattering characteristics of different aspect ratio diffusers at an incident wavelength of 0.03 m was obtained.