Ground Penetrating Radar

Ground penetrating radar (GPR) is used in civil engineering, archaeology, and many other areas. GPR antennas are moved over the surface of the inspected soil or structure, while emitting and receiving electromagnetic (EM) waves. In order to extract accurate and useful information from the received EM field, it is important to have as much a priori information as possible [1]. Such information includes a good understanding of the electromagnetic properties of the involved media and used antennas [2]. However, the knowledge about these properties is inevitably stochastic in its nature.

Many researchers have studied the EM behaviour of GPR antennas, by using different techniques that can be classified in two main categories: frequency domain (FD) [3] and time domain (TD) [4]-[10] techniques. A stochastic analysis of the transient response of a GPR antenna has been presented in [11]-[13]. In [11] the unknown current along the wire above the lossy-half space is governed by the space-time Hallen integral equation. The deterministic solution is featured by GB-IBEM method. The stochastic response is obtained with respect to uncertain antenna position (height) and uncertain ground conductivity. The work done in [12] and [13] present the stochastic current response for the wire buried in the lossy ground which may be found useful not only in GPR purposes but in other areas, for example in the design of lighting protection for electrical settlements.

As a counterpoise to time domain analysis, the stochastic analysis of frequency domain response is presented in the present paper. Stochastic Collocation (SC) method is combined with a direct EM solver to assess the variability of the current induced on a GPR dipole antenna, due to the uncertain nature of the soil and antenna height. The dipole is assumed to be thin and is placed above a lossy half-space, with its axis parallel to the air-soil interface: such simple geometry is especially convenient for testing new computational approaches and methods. The formulation of the problem, implemented in our deterministic EM solver, is based on a FD solution of Pocklington's integro-differential equation, by means of Galerkin-Bubnov Indirect Boundary Element Method (GB-IBEM) [3]; the transient response is then obtained via inverse Fast Fourier's transform [14].

The paper is organized as follows. Section 2 outlines the employed FD integral equation approach and related numerical solution (Sub-section 2.1); the theoretical basis of the Stochastic Collocation method are also presented (Sub-section 2.2). Section 3 brings computational examples, while in Section 4 general conclusions are given.

[1] H. M. Jol, Ground Penetrating Radar Theory and Applications, Amsterdam: Elsevier Science, 2009.

[2] C. Warren, N. Chiwaridzo, A. Giannopoulos, “Radiation Characteristics of a High-Frequency Antenna in Different Dielectric Environments,” Proc. 15th International Conference on Ground Penetrating Radar – GPR 2014, 30 June - 4 July 2014, Brussels, Belgium, pp. 767–772, doi: 10.1109/ICGPR.2014. 6970529.

[3] D. Poljak and V. Doric, “Transmitted field in the lossy ground from ground penetrating radar (GPR) dipole antenna,” Computational Methods and Experimental Measurements XVII 3, vol. 59, WIT Press, pp. 3-11, 2015, doi: 10.2495/CMEM150011.

[4] A. Giannopoulos, “Modelling ground penetrating radar by gprmax,” Construction and Building Materials, vol. 19, no. 10, pp. 755-762, December 2005, doi: 10.1016/j.conbuildmat.2005.06.007.

[5] L. Gurel and U. Oguz, “Three-dimensional fdtd modelling of a ground penetrating radar,” IEEE Transactions on Geoscience and Remote sensing, vol. 38, no. 4, pp. 1513–1521, 2000, doi: 10.1109/APS.2000.874882.

[6] T. Weiland, “A discretization model for the solution of Maxwell's equations for six-component fields,” Archiv fuer Elektronik und Uebertragungstechnik, vol. 31, p. 116–120, 1977.

[7] D. Poljak, S. Sesnic, D. Paric, and K. El Khamlichi Drissi, “Direct Time Domain Modeling of the Transient Field Transmitted in a Dielectric Half-Space for GPR Applications,” Proceedings of the International Conference on Electromagnetics in Advanced Applications (ICEAA), 7–11 September 2015, Torino, Italy, pp. 345–348, doi: 10.1109/ICEAA.2015.7297133.

[8]D. Poljak, S. Sesnic, A. Susnjara, D. Paric, K. El Khamlichi Drissi, S. Lallechere, “Direct time domain evaluation of the transient field transmitted into a lossy ground due to GPR antenna radiation,” Engineering Analysis with Boundary Elements, vol. 82, pp. 27–31, 2017, doi: 10.1016/j.enganabound. 2017.05.007.

[9] C. Warren, L. Pajewski, D. Poljak, A. Ventura, A. Giannopoulos, and S. Sesnic, “A comparison of Finite-Difference, Finite-Integration, and Integral-Equation methods in the Time Domain for modelling Ground Penetrating Radar antennas,” Proceedings of the 16th International Conference of Ground Penetrating Radar, 13–16 June 2016, Hong Kong, China, doi: 10.1109/ICGPR.2016. 7572676.

[10] C. Warren, S. Sesnic, A. Ventura, L. Pajewski, D. Poljak, and A. Giannopoulos, “Comparison of Time-Domain Finite-Difference, Finite-Integration, and Integral-Equation Methods for Dipole Radiation in Half-Space Environments,” Progress In Electromagnetics Research M, vol. 57, pp. 175–183, 2017, doi: 10.2528/PIERM17021602.

[11] S. Lalléchère, S. Antonijevic, K. El Khamlichi Drissi, and D. Poljak, “Optimized Numerical Models of Thin Wire above an Imperfect and Lossy Ground for GPR Statistics,” Proc. International Conference on Electromagnetics in Advanced Applications (ICEAA), 7–11 September 2015, Torino, Italy, pp. 907–910, doi: 10.1109/ICEAA.2015.7297246.

[12] S. Lalléchère, S. Sesnic, P. Bonnet, K. El Khamlichi Drissi, F. Paladian, D. Poljak, “Sensitivity analysis of the time transient currents induced along thin wires buried in lossy and uncertain environments,” Proceedings of the 11th European Conference on Antennas and Propagation (EUCAP 2017), 19–24 March 2017, Paris, France doi: 10.23919/EuCAP.2017.7928291.

[13] S. Sesnic, S. Lalléchère, D. Poljak, and K. El Khamlichi Drissi, “Stochastic collocation analysis of the transient current induced along the wire buried in a lossy medium,” Computational Methods and Experimental Measurements XVII, Southampton, WIT Press, pp. 47–58, 2015, doi: 10.2495/CMEM150051.

[14] A. Susnjara, D. Poljak, S. Sesnic, and V. Doric, “Time Domain and Frequency Domain Integral Equation Method for the Analysis of Ground Penetrating (GPR) Antenna,” Proceedings of the 24th International Conference on Software, Telecommunications and Computer Networks (SoftCOM 2016), 22–24 September 2016, Split, Croatia, pp. 1–4, doi: 10.1109/SOFTCOM.2016.7772184.

[15] Matlab Version 7.11.0.584 (R2010b), Massachusetts: The MathWorks Inc, 2010.

[16] S. Lalléchère, P. Bonnet, and F. Paladian, “Electrical stochastic modelling of cell for bio-electromagnetic compatibility applications,” Annals of Telecommunications, vol. 69, pp. 295–308, 2014, doi: 10.1007/s12243-013-0364-9.

[17] H. Dodig, S. Lalléchère, P. Bonnet, and K. El Khamlichi Drissi, “Stochastic sensitivity of the electromagnetic distributions inside a human eye modeled with 3D hybrid BEM/FEM edge element method,” Engineering Analysis with Boundary Elements, vol. 49, pp. 48–62, 2014, doi: 10.1016/j.enganabound. 2014.04.005.

[18] A. Saltelli, M. Ratto, T. Andres, F. Campolongo, J. Cariboni, D. Gatelli, M. Saisana, and S. Tarantola, Global Sensitivity Analysis: The Primer, Ed. Wiley, January 2008.

[19] D. Poljak, Advanced Modeling in Computational Electromagnetic Compatibility. Hoboken, NJ: Wiley, 2007.

For information concerning COST Action TU1208 and TU1208 GPR Association, please take contact with the Chair of the Action and President of the Association, Prof. Lara Pajewski. From 4 April 2013 to 3 October 2017, this website was supported by COST, European Cooperation in Science and Technology - COST is supported by the EU RTD Framework Programme Horizon2020. TU1208 Members are deeply grateful to COST for funding and supporting COST Action TU1208. As of 4 October 2017, this website is supported by TU1208 GPR Association, a non-profit association stemming from COST Action TU1208.