一种改进的快速计算多层媒质闭式格林函数的直接DCIM

An improved direct DCIM for fast calculation of the closed-form Green's functions in multilayered media

Somm erfeld积分是计算多层媒质空域格林函数必须首先解决的问题,该文提出一种对直接DC IM的改进方法,与传统的一级和二级DC IM相比,这种方法求解得到的空域格林函数在近场区、中间场区和远场区都是准确的,并且不用提取准动态项和表面波分量,从而克服了传统DC IM提取这些项的困难.与直接DC IM相比,这种方法将直接DC IM中第一级近似采用的路径一分为二,在不同的路径上采用不同的采样参数,从而在不降低计算精度的前提下,通过减少总的采样点数,有效地减少计算量,缩短CPU时间,达到快速计算格林函数的目的.通过对微带结构格林函数的计算,数值仿真结果与相关文献吻合很好,证实了该方法的正确性.

Sommerfeld integration was the key problem which need to be solved in calculating the spatial-domain Green＇s functions （GF） in muhilayered media. In the paper, an improved direct DCIM was proposed. Compared with the traditional one-level and two-level DCIM, the spatial-domain GF obtained by the method was accurate both in the near, intermediate and far-field regions without any quasi-dynamic and surface -wave extraction. So the difficulty the traditional DGIM had in extracting those quantities was overcome. Compared with the direct DCIM, the method separated the first level path of direct DCIM into two parts, and different numbers of samples were adopted on different paths. So the intention of fast-calculating the spatial-domain GF accurately was achieved with the computational load and the CPU-times reduced effectively by decreasing the total number of samples. The GF results obtained from a microstrip case were consistent with relevant literature, which confirmed the correctness of this method.