In addition, when the ground conductivity
is 0.005 S/m, the strong electromagnetic wave reflected from the DBC leads to an enormous deviation in the numerical solution, whereas the CFS-PML still exhibits good absorption; in this case, the average relative errors of the DBC and CFS-PML are 42.9% and 4.17%, respectively.
The penetration depth is dependent on various factors but mostly the ground conductivity
and the EM wave frequencies (Yaccup and Brabham, 2012), when the quality of data acquired is influenced by the ambient electromagnetic noise.
Here a Hertzian (small) dipole with dipole moment p directed to positive X axis, at altitude xo above the infinite, flat and lossy ground, radiates time-harmonic electromagnetic (EM) waves at angular frequency [omega] = 2[pi]f Here the relative complex permittivity of the ground is [[epsilon]'.sub.r] = [epsilon]'/[[epsilon].sub.0] = [[epsilon].sub.r] + i[sigma]/[omega][[epsilon].sub.0], a being the ground conductivity
, f the frequency of radiation and [[epsilon].sub.0] = 8,854 x [10.sup.-12] F/m is the absolute permittivity in vacuum or air.
 Geonics, EMD38-DD Ground Conductivity
Meter-Dual Dipole Version, Geonics, Ontario, Canada, 2005.
As can be seen in , it is difficult to reduce the peak transient grounding resistance (P-TGR) value by increasing the number of the grounding electrode or improving the topology of the grounding system at the assumed ground conductivity
meters for environmental site evaluation.
The measurements are then analyzed using a mathematical heat transfer model to estimate ground conductivity
and borehole resistance values.
The effects of ground conductivity
and field distortions are accommodated in the real-lime processing.
The electromagnetic method of geophysical observation was carried out using a ground conductivity
meters Geonics EM31.
In this application it is typically only used as a guide and is often carried out in conjunction with other tools such as ground conductivity
McNeill (1980) presented the theoretical basis for the use of electromagnetic (EM) ground conductivity
meters to map lateral variation in subsurface electrical conductivity.