Transient electromagnetic response of a three-dimensional body in a layered earth
Transient electromagnetic response of a three-dimensional body in a layered earth
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DOI：
10.1190/1.1442212
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发表时间：
1986-08
期刊：
影响因子：
3.3
通讯作者：
G. Newman;G. W. Hohmann;W. L. Anderson
中科院分区：
文献类型：
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作者：
G. Newman;G. W. Hohmann;W. L. Anderson
三维电磁散射问题首先在频域用电场体积积分方程表示。然后用正弦和余弦数字滤波器或衰减谱对三维响应进行傅里叶变换。将数字滤波技术应用于稀疏采样频率测深，在与数字滤波器卷积之前，用三次样条插值函数代替采样频率。通常，每十年需要5到8个点的20到40个频率才能得到准确的解决方案。计算出的瞬态从早期到后期衰减超过6个数量级后，通常是有误差的。衰减谱通常需要10个频率才能得到满意的解。然而，使用衰减谱的解决方案似乎不如使用数字滤波器的解决方案准确，特别是在早期之后。对三维解的检查包括频率的互易性和收敛性检查。
The three‐dimensional (3-D) electromagnetic scattering problem is first formulated in the frequency domain in terms of an electric field volume integral equation. Three‐dimensional responses are then Fourier transformed with sine and cosine digital filters or with the decay spectrum. The digital filter technique is applied to a sparsely sampled frequency sounding, which is replaced by a cubic spline interpolating function prior to convolution with the digital filters. Typically, 20 to 40 frequencies at five to eight points per decade are required for an accurate solution. A calculated transient is usually in error after it has decayed more than six orders in magnitude from early to late time. The decay spectrum usually requires ten frequencies for a satisfactory solution. However, the solution using the decay spectrum appears to be less accurate than the solution using the digital filters, particularly after early times. Checks on the 3-D solution include reciprocity and convergence checks in the frequenc...