多台阶板电磁耦合散射试验测量与RCS估算

Multi-step-plane's Electromagnetic Coupling Scattering Experimental Measurement and RCS Estimation

台阶板在斜入射时的散射主要来自平板后向散射和台阶绕射回波的贡献,在一定条件下还有表面波的贡献。试验表明入射角大于5°时台阶的绕射回波是散射回波的主要组成部分。对于3台阶板,当台阶沿入射方向的距离为半波长的整数倍时,其散射回波相位相同,产生相干叠加使雷达散射截面(RCS)较大,在RCS曲线上反映为波峰。这些波峰的特点是台阶间距越大,波峰越多,且较高波峰与较低波峰交替出现。一种根据台阶散射的叠加估算多台阶板RCS的方法是用单台阶板和平板散射的试验结果按相位相减得到纯台阶的散射,再将平板的散射与多条纯台阶的散射按相位叠加。对3台阶板的预估结果与测试结果符合较好,预估结果的平均误差在3dB以内。

The scattering of a step-plane mainly consists of the backscattering induced by the plane-effect and the refraction of the plane; in addition,under certain conditions the surface wave may also be a contributing factor. Experimental results show that when the incident angle is more than 5°,refraction is the major part of the backscattering. For the tri-step-plane,when the step distance along the incident direction is the integral multiple of the half-wavelength,the scattering of the steps interferes and superposes on each other to result in an increased radar cross section （RCS） because the phase of backscattering is the same. Thus the RCS curve exhibits a crest at the correspondent incident angle. The pure scattering of a step can be obtained by subtracting the scattering of a mono-step-plane and that of a non-step-plane. A method to estimate the RCS of a multi-step-plane is to add the scattering of several pure steps to that of the non-step-planes according to the phase. The estimated result of a tri-step-plane conforms to the experimental result and the mean error is less than 3 dB.