The loop radius of the coincident‐loop system above a polarizable half‐space has a significant effect on the magnitude of the negative response and its time of occurrence. Computations are made to study this phenomenon for various values of the electrical parameters of the ground, which is described by a Cole‐Cole model. An optimum loop radius is found to exist, which leads to the largest peak of the negative response. It is found that for values of the frequency parameter (c) larger than 0.5, the largest peak of the negative response occurs at a time nearly equal to the Cole‐Cole time constant. Empirical formulas are deduced relating both the optimum loop radius and the largest peak of the negative response to the electrical parameters of the polarizable half‐space. The above phenomena may be used as a simple and effective guide for the detection of a polarizable target and estimating its electrical parameters.

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The aim of this work is to consider the phenomenon of negative response and its detectability in a polarizable half-space formed of Clay-water mixture which commonly exists in water aquifers and which can be used as a simple indicator of the presence of Underground water.We make use of an analytical treatment for the transient voltage induced in a coincident loop lying on a half-space as a basis for our computations. A Cole-Cole model is used to represent the Clay with appropriate parameters.As saturated Clay is characterized by high conductivity and moderate chargeability, it is hardly detectable relative to the practical noise level. However, there are optimum Clay parameters that offer a maximum negative response. It is also observed that for a very short time constant z in the Cole-Cole model, the amplitude of the negative response decreases with the decrease of the time constant due to the fast decay of the polarization current.Finally, it is found that there is an optimum value for the loop radius which gives the largest value of the negative response and this loop radius depends on the model parameters.

No abstract

The aim of this work is to consider the phenomenon of negative response and its detectability in a polarizable half-space formed of Clay-water mixture which commonly exists in water aquifers and which can be used as a simple indicator of the presence of Underground water.We make use of an analytical treatment for the transient voltage induced in a coincident loop lying on a half-space as a basis for our computations. A Cole-Cole model is used to represent the Clay with appropriate parameters.As saturated Clay is characterized by high conductivity and moderate chargeability, it is hardly detectable relative to the practical noise level. However, there are optimum Clay parameters that offer a maximum negative response. It is also observed that for a very short time constant z in the Cole-Cole model, the amplitude of the negative response decreases with the decrease of the time constant due to the fast decay of the polarization current.Finally, it is found that there is an optimum value for the loop radius which gives the largest value of the negative response and this loop radius depends on the model parameters.