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Electromagnetic induction antenna modelling using a linear system of complex antenna transfer functions
Author(s) -
Moghadas Davood,
André Frédéric,
Bradford John H.,
van der Kruk Jan,
Vereecken Harry,
Lambot Sébastien
Publication year - 2012
Publication title -
near surface geophysics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.639
H-Index - 39
eISSN - 1873-0604
pISSN - 1569-4445
DOI - 10.3997/1873-0604.2012002
Subject(s) - emi , antenna (radio) , calibration , geology , electromagnetic interference , dipole antenna , conductivity , remote sensing , acoustics , electronic engineering , electrical engineering , physics , engineering , quantum mechanics
The quantitative retrieval of soil apparent electrical conductivity using electromagnetic induction (EMI) has remained limited due to strong simplifications regarding EMI antenna modelling. In this paper, a new technique for EMI antenna modelling is applied for the common‐offset EMI systems. The EMI system is efficiently described using global transmission and reflection coefficients and Green's functions are used to describe wave diffusion for horizontal and vertical dipole modes. We performed EMI measurements along a 180‐metre‐long transect with two different instrument heights above the soil surface, as well as with different orientations and frequencies. To ensure proper retrieval of the soil apparent electrical conductivity, the reference values were obtained from electrical conductivity data measured from 11 undisturbed soil cores taken along the EMI transect. The apparent electrical conductivity values calculated by applying the proposed model have a good agreement with reference values, however some discrepancies can be observed that are mainly attributed to the presence of local heterogeneities and also errors due to the variations in the height of the EMI instruments above the ground. The proposed method appears to be promising for quantitative retrieval of soil apparent electrical conductivity and resolving calibration issues that are typically encountered using EMI. In addition, the model calibration (antenna transfer functions determination) was successfully accomplished using conductivity values measured from the soil cores.