层状大地频率域长导线源激发的电磁场

采用Fourier变换法从Maxwell方程组出发，导出了层状大地模型上接地长导线源激发的电磁场表达式。结果表明：接地长导线源实际上是2个接地电极和线电流源构成的一个组合源；其电磁场表达式表明平行于长导线方向的电场分量为2个接地电极激发的平行于长导线方向的电场分量和线电流激发的电场的叠加，垂直于长导线方向的电场分量和电场的垂直分量均是2个接地电极激发的；平行于长导线方向的磁场分量由2个接地电极所激发，而垂直于长导线方向的磁场分量为2个接地电极激发的垂直于长导线方向的磁场分量和线电流激发的磁场的叠加，磁场的垂直分量为线电流源所激发。进一步的结果分析表明，在均匀半空间上、大收发距时，2个接地电极激发的平行于长导线方向的电场分量和线电流激发的电场分量是相等的，2个接地电极激发的垂直于长导线方向的磁场分量和线电流激发的磁场分量是相等的，且它们的振幅与2个电极之间的距离成正比。

Electromagnetic Fields Excited by Long Line Sources in Frequency Domain on Layered Earth Model

The Fourier transformation is adopted to solve directly the Maxwell’s equations and we get the electromagnetic fields excited by the long grounding source on the layered earth model. Results show that the long grounding source is combination of two grounding poles and line current source. The electrical component parallel to the long grounding line can be decomposed into two parts: one excited by the two grounding poles, the other excited by the line current source.The electrical component perpendicular to the long grounding line and the vertical electrical component are excited by only the two poles. For magnetic fields, the component parallel to the long grounding line is excited by the grounding poles.The component vertical to the long grounding line is decomposed into two parts: one excited by the two grounding poles, the other excited by the line current source.The vertical magnetic fields is excited by the line current source. For homogeneous earth model, at large distance, the electrical component parallel to the long grounding line excited by the two grounding poles is equal to the electric field excited by the line current source and the magnetic field perpendicular to the long grounding line excited by the two grounding poles is equal to the magnetic field excited by the line current source. Their amplitude is proportional to the distance between two grounding poles.