View in EDS

Development of an opposing coils frequency domain electromagnetic method transmitter.

Saved in:

Bibliographic Details
Title:	Development of an opposing coils frequency domain electromagnetic method transmitter.
Authors:	Guo, Tao¹ (AUTHOR), Liu, Qingbin² (AUTHOR), Xi, Zhenzhu¹ (AUTHOR) xizhenzhu@163.com, Zhang, Zhiqing³ (AUTHOR), Qi, Qingxin² (AUTHOR), Chen, Xingpeng² (AUTHOR), Diao, Huatao² (AUTHOR)
Source:	Journal of Applied Geophysics. Oct2025, Vol. 241, pN.PAG-N.PAG. 1p.
Subjects:	Alternating current circuits, Electric transients, Spatial resolution, Field research, Electric inductance
Abstract:	The frequency-domain electromagnetic (FDEM) method is widely applied in near-surface geophysical investigations. However, traditional bistatic FDEM sensors often exhibit low spatial resolution, while monostatic designs such as gradient and bucking coils face challenges due to structural complexity and limited anti-interference capabilities. Opposing coils, a weak-coupling configuration commonly used in transient electromagnetic (TEM) methods, have shown promising performance. Based on the equivalence between time and frequency domains, this study aims to fabricate an FDEM transmitter using opposing coils to verify its performance in frequency domain. A prototype transmitter was developed using a full-bridge circuit to generate alternating current from a battery source, with an absorption circuit added for circuit protection. To overcome high-frequency suppression caused by coil inductance, series resonance was employed to increase emission current. Two relay control schemes were tested, and the causes of abnormal pulse phenomena were analyzed. Field experiments comparing the prototype with the commercial GEM-2 system demonstrate that the prototype—featuring stronger transmission currents and an opposing-coil configuration—yields higher signal amplitudes and more distinct anomalies. These results indicate enhanced spatial resolution and sensitivity to shallow subsurface features, underscoring the effectiveness of opposing coil designs for improving near-surface FDEM imaging. • Applying opposing coils to frequency-domain EM enhances spatial resolution and anti-interference. • Optimized absorption circuits and relay arrays boost emission current and theoretical detection depth. • Experiments show the opposing-coils FDEM method has higher resolution and anti-interference. [ABSTRACT FROM AUTHOR]
	Copyright of Journal of Applied Geophysics is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
Database:	Engineering Source

Description
Abstract:	The frequency-domain electromagnetic (FDEM) method is widely applied in near-surface geophysical investigations. However, traditional bistatic FDEM sensors often exhibit low spatial resolution, while monostatic designs such as gradient and bucking coils face challenges due to structural complexity and limited anti-interference capabilities. Opposing coils, a weak-coupling configuration commonly used in transient electromagnetic (TEM) methods, have shown promising performance. Based on the equivalence between time and frequency domains, this study aims to fabricate an FDEM transmitter using opposing coils to verify its performance in frequency domain. A prototype transmitter was developed using a full-bridge circuit to generate alternating current from a battery source, with an absorption circuit added for circuit protection. To overcome high-frequency suppression caused by coil inductance, series resonance was employed to increase emission current. Two relay control schemes were tested, and the causes of abnormal pulse phenomena were analyzed. Field experiments comparing the prototype with the commercial GEM-2 system demonstrate that the prototype—featuring stronger transmission currents and an opposing-coil configuration—yields higher signal amplitudes and more distinct anomalies. These results indicate enhanced spatial resolution and sensitivity to shallow subsurface features, underscoring the effectiveness of opposing coil designs for improving near-surface FDEM imaging. • Applying opposing coils to frequency-domain EM enhances spatial resolution and anti-interference. • Optimized absorption circuits and relay arrays boost emission current and theoretical detection depth. • Experiments show the opposing-coils FDEM method has higher resolution and anti-interference. [ABSTRACT FROM AUTHOR]
ISSN:	09269851
DOI:	10.1016/j.jappgeo.2025.105847