FDTD法建模中激励源的选择与设置

Selection of source in FDTD modeling

FDTD法建模中 ,除了需要在足够的网格空间中模拟被研究的媒质外 ,合理进行激励源的建模也十分重要。因此 ,需要尽可能将源的特性与实际物理模型性质一致。本文给出了电流源作为激励源情况下的 FDTD方程 ,并给出了运用 FDTD法计算不同激励源下 ,散热片的辐射电平的计算结果。结果表明 :叠加法得到的场反射系数小 ,激励源附近的场误差较大 ,所以激励源需要远离计算边界。不同激励源作用下 ,散射体的电磁特性不同 ,因此在分析散热片的电磁辐射特性时 ,需要采用 SPICE或其它电路分析工具确定电路的实际电参数 ,根据这些电参数得到激励源模型 。

It is very important to model source reasonably beside that medium was simulated in enough space in FDTD modeling, because different source models can produce different electromagnetic characteristics. In this paper, there are the FDTD equations about current source and the results of radiation of heatsink using different sources. It is shown that the reflection of added source is smaller than replaced source and the errors near source is biggest. Electromagnetic emission of heatsink can be predicted according to actual source model from electric parameters using SPICE or the other circuit analysis.