中文摘要：

为了推动有源电磁法的场区划分由定性向定量发展，提出一种新的可控源电磁法场区划分方法。定义电场强度Ex、磁场强度Hy和阻抗Zxy的衰减率，计算分析均匀半空间和2层模型的轴向和赤道模式Ex、Hy和Zxy的衰减率，揭示水平电偶极子源电磁波衰减率随收发距（感应数）的变化规律；基于均匀半空间Ex，Hy和Zxy的衰减率进行场区划分，讨论Ex，Hy和Zxy衰减率在不同场区的衰减特性。研究结果表明：轴向和赤道模式下的Ex，Hy和Zxy衰减特征有较大区别；当衰减率容许误差为1‰时，轴向模式下Ex，Hy和Zxy进入远区的感应数分别为11.450，6.994和12.294，进入远区的顺序为Hy，Ex，Zxy；在赤道模式下，Ex，Hy和Zxy进入远区的感应数分别为9.198，9.924和10.915，进入远区的顺序为Ex，Hy，Zxy。

英文摘要：

In order to promote the development of EM fields’ division method from qualitative to quantitative, a novel method for CSEM （control source electromagnetic method） fields’ division was proposed. A new attenuation rate was defined for electric field strength Ex, magnetic field strength Hy, and impedance Zxy. Based on the new attenuation rate, the propagation characteristics of Ex, Hy and Zxy were studied, and the attenuation rate change of the HED （horizontal electric dipole） source electromagnetic wave with the change of the offset （induction number） was revealed. Based on the attenuation rate of Ex, Hy and Zxy which was calculated by homogeneous half space model, the EM fields’ division was proposed. The attenuation characteristic in near field, transition field and far field was studied. The results show that there is difference between equatorial and axial mode in EM fields’ attenuation. The induction numbers of Ex, Hy and Zxy are 11.450, 6.994, 12.294 when they change into far field in axial direction. The induction numbers of Ex, Hy and Zxy are 9.198, 9.924 and 10.915, respectively, when they change into far field in equator direction.