Sensitivity of metal detectors to spheroidal targets

Silvester, P.; Omeragić, Dževat

doi:10.1109/36.477191

Cited by 13 publications

(9 citation statements)

References 5 publications

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“…Using demagnetization factors tabulated by Osborne (1945) or formulas by Silvester and Omeragic (1995) as discussed in Smith and Morrison (2006), for a prolate ellipsoid with axial ratio 3:1, the demagnetization factors become D 1 ¼ 0:112ðaxialÞ; and D 2 ¼ D 3 ¼ 0:444ðtransverseÞ:…”

Section: Flux Gathering and Demagnetizationmentioning

confidence: 99%

Fast approximate EM induction modeling of metallic and UXO targets using a permeable prism

Asten

Duncan²

2007

Journal of Applied Geophysics

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Section: Flux Gathering and Demagnetizationmentioning

confidence: 99%

Fast approximate EM induction modeling of metallic and UXO targets using a permeable prism

Asten

Duncan²

2007

Journal of Applied Geophysics

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“…However the method using electromagnetic wave is dominant, and recently the method using superconducting coil has been attempted [8,9]. Theoretical analysis [10,11] and sensitivity analysis [12,13] along with the shape of metal sensor have been performed to explore the sensitivity of electromagnetic metal sensor. On the other hand, there were attempts [14] to enhance visibility of metal piece through signal processing.…”

Section: Introductionmentioning

confidence: 99%

Two-Channel Metal Detector Using Two Perpendicular Antennas

Choi

2014

Journal of Sensors

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Two-channel metal detector, having two sets of perpendicularly oriented sensor antennas, is proposed to expand detectable size, ranging from mm through cm scale, of metal sensor, while conventional metal sensor is dedicated for detection only in mm or cm scale. The characteristics of the two metal detection sensor channels were investigated, respectively, and the interference effect, while in simultaneous operation, between two sensor channels was discussed. Metal detection channel, having sensitivity in mm scale, showed detectable sensitivity to moving ferrous sphere, with diameter down to 0.7 mm, at 50 kHz exciting frequency and enhanced sensitivity distribution. And metal detection channel having sensitivity in cm scale showed more uniform sensitivity distribution with the flexibility for future modular construction. The effect of interference, while in simultaneous operation of two sensors, resulted in reduced output response, but still within usable detection range. Thus it was feasible to operate two sensors, having different sensitivity range, simultaneously and to extend detection range from mm to cm scale, within practically acceptable interference.

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“…The high frequency limit polarizabilities m z (ω=∞) and m t (ω=∞) for a conducting spheroid are given by the same formulae with permeability artificially set to zero (e.g., Silvester and Omeragic, 1995). We approximate the transverse polarizability m t using that of a sphere of the transverse diameter 2a = 2a.…”

Section: Approximationmentioning

confidence: 99%

“…Following Silvester and Omeragic (1995), for axial magnetic field H z , the magnetization inside the spheroid is given by…”

Section: Appendix: Spheroid Frequency Limitsmentioning

confidence: 99%

Approximating spheroid inductive responses using spheres

Smith

Morrison

2006

GEOPHYSICS

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The response of high permeability (µ r ≥ 50) conductive spheroids of moderate aspect ratios (0.25 to 4) to excitation by uniform magnetic fields in the axial or transverse directions is approximated by the response of spheres of appropriate diameters, of the same conductivity and permeability, with magnitude rescaled based on the differing volumes, D.C. magnetizations, and high frequency limit responses of the spheres and modelled spheroids.

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Sensitivity of metal detectors to spheroidal targets

Cited by 13 publications

References 5 publications

Fast approximate EM induction modeling of metallic and UXO targets using a permeable prism

Fast approximate EM induction modeling of metallic and UXO targets using a permeable prism

Two-Channel Metal Detector Using Two Perpendicular Antennas

Approximating spheroid inductive responses using spheres

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