Insertion loss due to a magnetically permeable spherical shell covering a concentric conducting target

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Published: Jan 1, 1993
DOI: https://doi.org/10.22201/igeof.00167169p.1993.32.1.1365
Keywords:
Electro-magnetic survey, Mineral exploration

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P. D. Saraf
National Geophysical Research Institute, Hyderabad, India
D. Indira Nagubai
National Geophysical Research Institute, Hyderabad, India

Abstract

A layered section in a uniform electromagnetic field is assumed to have two concentric spherical shells (in nongalvanic contact). Such targets may occur in native copper deposits viz., conducting ore bodies surrounded by a halo of altered rocks. It is found that (a) changes in characteristic properties of overburden and/or ore formations cause significant distortions in the geoelectromagnetic parameters and may change the detection sensitivity in some bands of frequencies; (b) multifrequency measurements afford the possibility of seeing beneath highly conducting layers; and (c) the variation of the shielding parameter with frequency exhibits, qualitatively, different patterns for conductive and resistive covers and may help distinguishing EM anomalies due to conductive and resistive overburden formations. The results may be useful in (1) understanding the shielding phenomenon in complex geological situations, and (2) providing background information (i.e. shielding behaviour of overlying or surrounding formations) against which geoelectromagnetic experiments can be planned.

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How to Cite
Saraf, P. D., & Indira Nagubai, D. (1993). Insertion loss due to a magnetically permeable spherical shell covering a concentric conducting target. Geofisica Internacional, 32(1), 167–173. https://doi.org/10.22201/igeof.00167169p.1993.32.1.1365
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Vol. 32 No. 1 (1993): January 1, 1993
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Article
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References

PARASNIS, D. S., 1973. Mining Geophysics. (Elsevier, Amsterdam).

SCHULZ, R. B., V. C. PLANTZ and D. R. BRUSH, 1968. Low frequency shielding resonance. IEEE Trans, on EM compatibility, EMC10, 1, 7-15. DOI: https://doi.org/10.1109/TEMC.1968.302901

NAGUBAI, D. I. and P. D. SARAF, 1993. Multifrequency electromagnetic response of a permeable cover target system. Bolletino di Geofisica. (In press).

NAGUBAI, D. I. and P. D. SARAF, 1991. Response resolution of shielded conductors through multifrequency EM measurements. A review Indo-US Workshop on EM Induction, Jan 13-14, 1991 held at IIT, Kharagpur, West Bengal.

NEGI, J. G., K. N. RAO and U. RAVAL, 1976. Insertion loss due to spherical shell in low-frequency zone. IEEE Trans., on Ant. and Wave Propagation, Vol. AP 12(4), 389-392. DOI: https://doi.org/10.1109/TAP.1976.1141349

NEGI, J. G. and P. D. SARAF, 1984. Multifrequency electromagnetic response of a shielded conductor, Geophys. Int., 23, 1, 1-15. DOI: https://doi.org/10.22201/igeof.00167169p.1984.23.1.793