等值反磁通瞬变电磁法天线零磁通面位置的确定方法

A method for determining the position of zero magnetic flux plane of antennae using the opposing-coils transient electromagnetic method

确定零磁通面几何位置是等值反磁通瞬变电磁法探测系统的关键。为此,提出了一种调零方法:用等值反磁通瞬变电磁仪连续发送固定频率的双极性方波,接收机实时采集接收天线的时间域信号,并使用离散傅里叶变换分别计算出粗调、细调和微调接收天线位置的最小功率谱密度(A1、A2、A3),当A1>A2>A3时,接收天线处于零磁通面。发送20 kHz双极性方波试验的结果表明,当A1>A2>A3时,二次场衰减信号过渡过程得到明显改善。该方法可为高性能等值反磁通瞬变电磁仪器的设计和制造提供参考。

Determining the geometric position of the zero magnetic flux plane is the key to the detection system of the opposing-coils transient electromagnetic method(opposing-coils TEM).Given this,a zeroing method was proposed in this study.First,an opposing-coils transient electromagnetometer was used to continuously send the bipolar square wave of fixed frequency.Then,the receiver collected the time domain signals of the receiving antenna in real time,and the discrete Fourier transform was used to calculate the minimum power spectral density(A1,A2 and A3)at the roughly-,finely-,and micro-tuned receiving antenna positions.When A1>A2>A3,the receiving antenna was in the zero magnetic flux plane.Finally,the test results of transmitting 20 kHz bipolar square wave showed that the transition process of the attenuation signals of the secondary field can be significantly improved under the condition of A1>A2>A3.