多元Pade逼近结合FDTD法快速获取柱体宽角度和宽频带RCS

Fast Calculation of Wide Angle and Wide Band RCS Pattern of 2-D Cylinders Using the FDTD Method Combined with Pade Interpolation Technique

计算散射问题时 ,采用 FDTD法可以很好地解决散射体比较复杂的一类问题。FDTD法的时域特征使得获取频率响应比较容易。但是 ,一般来说 ,FDTD法迭代计算的时间比较长。当计算散射体宽角度 RCS时 ,每变换一个角度 ,就需要重新用 FDTD法计算一次。同样 ,近远区时频变换也要消耗较多的计算时间。引入 Pade多元逼近技术 ,可以大大节省计算时间。对FDTD法计算获得的、稀疏的 RCS响应进行逼近 ,然后用获得的 Pade二元逼近式同时计算宽角度和宽频带 RCS响应。文中采用了最小二乘法 ,进行全局约束 ,以充分利用已有信息 ,达到最佳逼近的效果。计算结果表明 Pade有理逼近式能很好地逼近 FDTD法精确计算的曲线 。

When the analyzed cylinders are rather complex, the FDTD method is very suitable to analyze this kind of scattering problems. But usually the iterative time of FDTD method is quite long, the iterative calculation of FDTD method is needed to perform at many angles in this case. Besides, it is necessary to perform a large number of near-far field transformation when the wide band RCS is computed. In this article, the multivariate Pade interpolation technique is employed to obtain wide-angle and wide-band results with satisfactory accuracy. By use of RCS results, which are obtained using FDTD method, the two-variable rational function of RCS pattern can be achieved. Then the wide-angle and wide-band RCS pattern can be calculated by use of the rational function. The least square method is adopted to make full use of the RCS results from FDTD method as possible.