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Proceedings Paper

Coil design considerations for a high-frequency electromagnetic induction sensing instrument
Author(s): John Brevard Sigman; Benjamin E. Barrowes; Yinlin Wang; Hollis J. Bennett; Janet E. Simms; Donald E. Yule; Kevin O'Neill; Fridon Shubitidze
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Paper Abstract

Intermediate electrical conductivity (IEC) materials (101S/m < σ < 104S/m), such as carbon fiber (CF), have recently been used to make smart bombs. In addition, homemade improvised explosive devices (IED) can be produced with low conducting materials (10-4S/m < σ < 1S/m), such as Ammonium Nitrate (AN). To collect unexploded ordnance (UXO) from military training ranges and thwart deadly IEDs, the US military has urgent need for technology capable of detection and identification of subsurface IEC objects. Recent analytical and numerical studies have showed that these targets exhibit characteristic quadrature response peaks at high induction frequencies (100kHz − 15MHz, the High Frequency Electromagnetic Induction (HFEMI) band), and they are not detectable with traditional ultra wideband (UWB) electromagnetic induction (EMI) metal detectors operating between 100Hz − 100kHz. Using the HFEMI band for induction sensing is not so simple as driving existing instruments at higher frequencies, though. At low frequency, EMI systems use more wire turns in transmit and receive coils to boost signal-to-noise ratios (SNR), but at higher frequencies, the transmitter current has non-uniform distribution along the coil length. These non-uniform currents change the spatial distribution of the primary magnetic field and disturb axial symmetry and thwart established approaches for inferring subsurface metallic object properties. This paper discusses engineering tradeoffs for sensing with a broader band of frequencies ever used for EMI sensing, with particular focus on coil geometries.

Paper Details

Date Published: 17 May 2016
PDF: 6 pages
Proc. SPIE 9823, Detection and Sensing of Mines, Explosive Objects, and Obscured Targets XXI, 982302 (17 May 2016); doi: 10.1117/12.2223988
Show Author Affiliations
John Brevard Sigman, Thayer School of Engineering at Dartmouth (United States)
Benjamin E. Barrowes, U.S. Army Engineer Research and Development Ctr. (United States)
Yinlin Wang, Thayer School of Engineering at Dartmouth (United States)
Hollis J. Bennett, U.S. Army Engineer Research and Development Ctr. (United States)
Janet E. Simms, U.S. Army Engineer Research and Development Ctr. (United States)
Donald E. Yule, U.S. Army Engineer Research and Development Ctr. (United States)
Kevin O'Neill, Thayer School of Engineering at Dartmouth (United States)
Fridon Shubitidze, Thayer School of Engineering at Dartmouth (United States)


Published in SPIE Proceedings Vol. 9823:
Detection and Sensing of Mines, Explosive Objects, and Obscured Targets XXI
Steven S. Bishop; Jason C. Isaacs, Editor(s)

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