有耗平面和三维目标复合散射的FDTD分析

采用FDTD方法计算了有耗地面与三维目标的复合散射,对吸收边界条件,连接边界条件和近远场变换作了细致讨论.吸收边界使用了广义PML吸收层,它对电磁波有较好的吸收效果.连接边界处则利用解析入射波和三波迭加技术,上半平面用入射波和反射波、下半平面用透射波作为对目标的外加场进行计算.得到近场数据后,为避免出现复杂的Sommerfeld积分,用互易原理简化了外推过程.FDTD算法与矩量法和快速多层多极子相比,具有节省内存,计算时间短等优点.通过地上物体和地下物体的计算验证了FDTD方法的精确性,讨论了散射体离地高度对后向RCS的影响.

The FDTD analysis for scattering of 3-dimensional target and lossy half-space

This paper employs the FDTD technology to study electromagnetic (EM) scattering of 3-dimensional target and a lossy half-space. It has been found that the original construction of PML cannot effectively absorb evanescent waves, and significant reflection can appear as PML is applied to terminate lossy media. The generalized PML can work very well in this case. To implement the near-to far field formation, the fields radiated by the surface currents are calculated using the reciprocity theorem. Numerical results show excellent agreement between our technique and some previous results. Some effects of the target height above the surface etc. on the RCS measurement are also discussed.