Effects of soil electromagnetic properties on metal detectors

Das, Yogadhish

doi:10.1109/tgrs.2006.870401

Cited by 70 publications

(48 citation statements)

References 21 publications

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“…In the past, because of the lack of available analytical techniques for evaluating (1)-(3), the conventional approach was to assume the hypothesis of quasi-static field, which consists of neglecting the effects of the displacement current in both the air and the ground [4][5][6]. The chief drawback of the solutions obtained under this assumption is that, when used for acquiring information about the ground subsurface, they do not permit to interpret high-frequency measurement data.…”

Section: Theorymentioning

confidence: 99%

“…It is well known that measuring the EM field produced by a currentcarrying insulated wire loop lying on the surface of a terrestrial area makes it possible to acquire information about the subsurface structure [1][2][3][4][5][6]. In particular, when the soil properties do not vary spatially, the presence of shallow buried objects such as mines, metals, or mineral resources can be detected by the departure of the recorded time-or frequency-domain experimental data from the theoretical results obtained regarding the ground as a homogeneous conducting half-space [1][2][3][4][5]7].…”

Section: Introductionmentioning

confidence: 99%

“…The small loop assumption is reasonable, since the diameter of the source is in most cases small if compared to both the source-receiver distance and the free-space wavelength. A number of analytical and semianalytical techniques have been recently developed for evaluating the time-and frequency-domain complete integral expressions for the EM field components produced by a VMD placed above the surface of a material half-space [1][2][3][4][5][6][8][9][10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

“…In particular, closed-form solutions in the frequency-domain have been derived under the quasi-static field assumption [4,6], that is neglecting the high-frequency effects due to the displacement currents in both the air and the ground. Such solutions constitute the preferred choice when the measurement data to be interpreted are in terms of mutual impedance between source and receiver loops (that is the voltage induced in the receiver loop per unit current flowing in the source loop [1,5,6,8,14]), but unfortunately are valid only in the lowfrequency range.…”

Section: Introductionmentioning

confidence: 99%

“…Such solutions constitute the preferred choice when the measurement data to be interpreted are in terms of mutual impedance between source and receiver loops (that is the voltage induced in the receiver loop per unit current flowing in the source loop [1,5,6,8,14]), but unfortunately are valid only in the lowfrequency range.…”

Section: Introductionmentioning

confidence: 99%

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Exact Electromagnetic Field Excited by a Vertical Magnetic Dipole on the Surface of a Lossy Half-Space

Parise¹

2010

PIER B

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Abstract-A rigorous analytical procedure is developed that allows the exact evaluation of the complete integral representations for the time-harmonic electromagnetic (EM) field components generated by a vertical magnetic dipole (VMD) lying on the surface of a flat and homogeneous lossy half-space. Closed-form expressions for the radial distributions of the EM field components induced on the surface of the half-space are provided in terms of exponential functions and modified Bessel functions. Such expressions make it possible to overcome the limitations implied by the previously published quasi-static solutions, which are valid only in the low-frequency range. Numerical results are presented to show where the quasi-static approximations deviate from the exact solutions for a given homogeneous medium as frequency is changed. The computed amplitude and phase frequency spectra of the EM field components demonstrate that the quasi-static approach produces inaccurate results at frequencies higher than 1 MHz, and that, in particular, it leads to underestimating the EM field strength. Finally, it is also shown that at a frequency equal to or greater than 10 MHz excellent results in terms of accuracy may be obtained by using the high-frequency asymptotic forms of the exact solutions.

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Section: Theorymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Exact Electromagnetic Field Excited by a Vertical Magnetic Dipole on the Surface of a Lossy Half-Space

Parise¹

2010

PIER B

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Realistic simulation of GPR for landmine and IED detection including antenna models, soil dispersion and heterogeneity

Stadler,

Schennen,

Hiller

et al. 2023

Near Surface Geophysics

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Ground‐penetrating radar (GPR) is an effective tool for detecting landmines and improvised explosive devices (IEDs), and its performance is strongly influenced by subsurface properties as well as the characteristics of the target. To complement or replace labour‐intensive experiments on test sites, cost‐efficient electromagnetic wave propagation simulations using the Finite‐Difference Time‐Domain (FDTD) method are being increasingly used. However, to obtain realistic synthetic data, accurate modelling of signal alteration caused by dispersion, scattering of soil material, target contrast, shape, and inner setup, as well as the coupling effects of the antenna to the ground is required. In this study, we present a detailed 3D model of a shielded GPR antenna applied to various scenarios containing metallic and non‐metallic targets buried in different soils. The frequency‐dependent intrinsic material properties of soil samples were measured with the coaxial transmission‐line technique, while a discrete random media was used to implement the heterogeneity of a gravel based on its grain‐size distribution. Our simulations show very good agreement with experimental validation data collected under controlled conditions. We accurately reproduce the amplitude and frequency content, phase of target signals, subsurface's background noise, antenna crosstalk and its interference with target signals, and the effect of antenna elevation. The approach allows for systematic investigation of the effects of soil, target, and sensor properties on detection performance, providing insight into novel and complex GPR scenarios and the potential for a wide range of simulation possibilities for demining with GPR. These investigations have the potential to improve the safety and effectiveness of landmine and IED detection in the future, such as building a database for training deminers or developing automatic signal pattern recognition algorithms.This article is protected by copyright. All rights reserved

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Metal Detecting in Archaeology

Scott

2020

Encyclopedia of Global Archaeology

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Effects of soil electromagnetic properties on metal detectors

Cited by 70 publications

References 21 publications

Exact Electromagnetic Field Excited by a Vertical Magnetic Dipole on the Surface of a Lossy Half-Space

Exact Electromagnetic Field Excited by a Vertical Magnetic Dipole on the Surface of a Lossy Half-Space

Realistic simulation of GPR for landmine and IED detection including antenna models, soil dispersion and heterogeneity

Metal Detecting in Archaeology

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