In this paper, a model for the input impedance of a hot-wire electro-explosive device (EED) based on differential-mode measurements is proposed. The model represents the EED using three transmission line segments in cascade. The characteristics of each segment are estimated according to data reported in the literature and to measurements of the differential-mode input impedance of actual EEDs in the ultrahigh frequency range. The experimental procedure and model are presented in detail. In addition, the impedance measurements and the predictions of the proposed model are compared with previous results reported in the literature.

The complex permittivity of different types of soils in the ultrahigh frequency (UHF) is studied in this letter. A new model, whose inputs are the low-frequency conductivity and the volumetric water content, is proposed to estimate the complex permittivity of soils in UHF. The model is compared with complex-permittivity values of each soil in the UHF range, which are determined from two-port S-parameters measurements of a coaxial probe designed for material characterization. Results show that the model is in a good agreement with the measurements despite some differences in soils with high resistivity. The soil samples used in this study include locations where humanitarian demining operations are being conducted.

In this paper, we analyze the effect of the soil on the induced current in a buried wire excited by an external field in the ultrahigh frequency range. We use an extended version of the Messier model, which provides the electromagnetic (EM) properties of dispersive soils. Based on comparisons of the Messier model and experimental data, it is verified that this model can be used up to a frequency of about 4 GHz for wet soils. A buried straight wire is used for analyzing the soil effect on the EM coupling with an external plane wave impinging from the air. It is shown that the effects of the soil on the EM response of a wire are mainly (i) to modify its electrical length and (ii) to attenuate the incident wave and, as a consequence, the induced current in the wire. The accuracy of the path decomposition method is assessed. It is shown that this method can be used to estimate with reasonable accuracy the behavior of the induced current. Finally, we study the influence of the frequency‐dependence of the soil parameters on the EM coupling to a buried wire. We show that the dispersive nature of the soils affects the spectral content of induced currents in buried wires. Therefore, it can be concluded that the frequency dependence of the soil parameters should not be neglected in EM coupling calculations in the UHF range, especially for low resistivity soils (ρ < 300 Ωm, corresponding to wet soils).

In this paper we present the latest results of a research program on the use of ground penetrating radar and machine learning-based algorithms for humanitarian demining in Colombia. We describe the experimental setup developed, which includes a polarimetric GPR-UWB unit, a radar positioning system, and a control unit. We describe as well a soil characterization campaign and an IED classification technique based on Support Vector Machine.