本文对互感系数(M)进行分析得出,在双对数坐标系中,对于不同的大地导电率和电流频率参数,M曲线形态不变,只是相对位移。基于这一概念,研制成一种新型计算工具。此尺不仅能直读任一频率的平行接近的M值,同时还具备速算任一频率的不平行接近的平均M值。与习用的列线图或曲线图相比,实践证明,具有使用简便、计算迅速、读数准确等特点。 In this paper, the mutual inductance (M) analysis shows that in the double logarithmic coordinate system, for different conductivity and current frequency parameters of the earth, M curve shape unchanged, only the relative displacement. Based on this concept, developed into a new computing tool. This rule can not only directly read parallel M values ​​of any frequency, but also have the average M value of the non-parallel approach of any one of the frequencies. Compared with the conventional nomogram or graph, it has been proved that the method has the advantages of easy to use, rapid calculation and accurate reading.