深入研究了用于高频场线耦合分析的渐近法中等效短线长度取值对渐近法计算精度的影响。首先通过大量计算分析了不同等效短线长度对传输线上感应电流分布计算结果的影响，结果表明当任一等效短线长度为半波长时，渐近法计算结果不再可靠。其次对等效短线长度选择与导线长度的关系进行了分析，发现当传输线长度相对于导线间距较大时，必须适当增加等效短线的长度才能得到较为准确的沿线感应电流分布。这些研究结果为工程应用提供了有益指导。

The influence of two short equivalent lines’ length on the accuracy of the asymptotic method for analysing electromagnetic field coupling to transmission line at high frequency is investigated in detail. Firstly, the induced current distribution along the transmission line in terms of different lengths of two short lines is analyzed through numbers of calculations. It is indicated that the calculated induced current along the line by asymptotic method is not reliable when any one of the short equivalent lines is half wavelength long. Secondly, the dependence of the two short equivalent lines on the whole transmission line length is studied. Results show that when the length of the transmission line is much longer than the distance between two conductors, it is necessary to increase the suggested lengths of the equivalent short lines in order to get more accurate induced current along the line.(2013CB328900)