Ground Penetrating Radar
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Electromagnetic modelling and simulation of a high-frequency Ground Penetrating Radar antenna over a concrete cell with steel rods
Alessio Ventura and Lara Pajewski
Full text: PDF [3.2 MB, open access]
Supplementary Materials: ZIP [21.7 MB, open access]
Abstract: This work focuses on the electromagnetic modelling and simulation of a high-frequency Ground-Penetrating Radar (GPR) antenna over a concrete cell with reinforcing elements. The development of realistic electromagnetic models of GPR antennas is crucial for accurately predicting GPR responses and for designing new antennas. We used commercial software implementing the Finite-Integration technique (CST Microwave Studio) to create a model that is representative of a 1.5 GHz Geophysical Survey Systems, Inc. antenna, by exploiting information published in the literature (namely, in the PhD Thesis of Dr Craig Warren); our CST model was validated, in a previous work, by comparisons with Finite-Difference Time-Domain results and with experimental data, with very good agreement, showing that the software we used is suitable for the simulation of antennas in the presence of targets in the near field. In the current paper, we firstly describe in detail how the CST model of the antenna was implemented; subsequently, we present new results calculated with the antenna over a reinforced-concrete cell. Such cell is one of the reference scenarios included in the Open Database of Radargrams of COST Action TU1208 “Civil engineering applications of Ground Penetrating Radar” and hosts five circular-section steel rods, having different diameters, embedded at different depths into the concrete. Comparisons with a simpler model, where the physical structure of the antenna is not taken into account, are carried out; the significant differences between the results of the realistic model and the results of the simplified model confirm the importance of including accurate models of the actual antennas in GPR simulations; they also emphasize how salient it is to remove antenna effects as a pre-processing step of experimental GPR data. The simulation results of the antenna over the concrete cell presented in this paper are attached to the paper as ‘Supplementary materials.’
Keywords: Ground Penetrating Radar (GPR); electromagnetic modelling; Finite-Integration technique (FIT); antennas; TU1208 Open Database of Radargrams; concrete.
Electromagnetic simulations of Ground Penetrating Radar (GPR)  scenarios including realistic models of the antennas are not yet common. Accurate models of GPR antennas have been only occasionally developed during the past two decades -; rarely, they have been combined with realistic models of complex environments . In most cases, GPR electromagnetic simulations use hertzian dipoles or lines of current to represent the transmitting antennas; the physical structure of the receiving antennas is usually not included in the models and the electric field impinging on the receivers is calculated -. This simplified approach is customarily adopted because easier to implement and computationally cheaper; in fact, nowadays running realistic models of GPR scenarios is still a challenging task, notwithstanding computing power is increasing and becoming more accessible.
In this paper, we employed commercial software implementing the Finite-Integration technique (FIT)  (CST Microwave Studio) for modelling and simulating an antenna representative of a widely used high-frequency commercial device manufactured by Geophysical Survey Systems, Inc. (GSSI). All necessary information about the antenna was taken from Dr Craig Warren’s PhD Thesis , where the freeware tool GprMax3D  was used to develop a Finite-Difference Time-Domain (FDTD) model of the same antenna. It has to be noted that, in  and here, the numerical model does not exactly replicate the commercial antenna because the electromagnetic properties of some antenna materials are unknown, due to commercial sensitivity; the undisclosed values were estimated in  (the match between the real and synthetic crosstalk responses of the antenna in free-space was maximized, by using Taguchi's optimisation method). It is also worth mentioning that the FDTD model developed in  is currently included in the library of antennas of the open-source software gprMax [19, 20], therefore gprMax users can easily include this antenna into their simulations without having to build it step-by-step. The CST model that we developed was successfully validated via comparisons with synthetic and experimental data available in , in cooperation with colleagues from The University of Edinburgh (United Kingdom); such data were obtained with the antenna immersed in free space and in lossy dielectric environments, with and without a circular-section metallic target and some results of the performed comparisons were presented in a conference paper .
In Section 2 of the present paper, we describe in detail how we developed the CST Microwave Studio model of the antenna; this information was not included in . Then, in Section 3, we present new results that we obtained by simulating the antenna over a reinforced-concrete cell. Such cell is one of the reference scenarios included in the Open Database of Radargrams of COST Action TU1208  and hosts a series of five circular-section steel rods, having different diameters and/or embedded at different depths into the concrete . We compare results obtained by using the realistic CST antenna model, and results obtained by representing the transmitting antenna with a line of current and by neglecting the physical structure of the receiving antenna. The aim of this comparison is to confirm and further highlight the importance of including realistic models of the actual antennas in GPR simulations, whenever the objective of the simulations is to accurately replicate a real GPR response, or to exploit the simulation results into an inversion process. Moreover, the comparisons presented in this paper emphasize once more how strong are antenna effects, and therefore, how salient it is to develop methods for removing them as a pre-processing step of GPR data. The results of our simulations are attached to the paper as ‘Supplementary materials.’
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 A. Benedetto and L. Pajewski, Eds. “Civil Engineering Applications of Ground Penetrating Radar,” Publishing House: Springer International; Book Series "Springer Transactions in Civil and Environmental Engineering;" April 2015; e-book ISBN: 9783319048130; hardcover ISBN: 9783319048123; doi: 10.1007/9783319048130; 371 pp.
 L. Gurel and U. Oguz, “Three-dimensional FDTD modeling of a Ground-Penetrating Radar,” IEEE Transactions on Geoscience and Remote Sensing, vol. 38, no. 4, pp. 1513–1521, July 2000, doi: 10.1109/36.851951.
 S. Lambot, E. C. Slob, I. van den Bosch, B. Stockbroeckx, and M. Vanclooster, “Modeling of Ground-Penetrating Radar for accurate characterization of subsurface electric properties,'” IEEE Transactions on Geoscience and Remote Sensing, vol. 42, no. 11, pp. 2555–2568, November 2004, doi: 10.1109/TGRS.2004.834800.
 G. Klysz, X. Ferrieres, J. Balayssac, and S. Laurens, “Simulation of direct wave propagation by numerical FDTD for a GPR coupled antenna,” NDT & E International, vol. 39, no. 4, pp. 338–347, November 2006, doi: 10.1016/j.ndteint.2005.10.001.
 A. Ahmed, Y. Zhang, D. Burns, D. Huston, and T. Xia, “Design of UWB Antenna for Air-Coupled Impulse Ground-Penetrating Radar,” IEEE Geoscience and Remote Sensing Letters, vol. 13, no. 1, pp. 92–96, January 2016, doi: 10.1109/LGRS.2015.2498404.
 C. Warren, “Numerical modelling of high-frequency ground-penetrating radar antennas,” PhD Thesis, The University of Edinburgh, 2009 (available for download at http://hdl.handle.net/1842/4074 - last checked 17 May 2019).
 C. Warren and A. Giannopoulos, “Creating FDTD models of commercial GPR antennas using Taguchi's optimisation method,” Geophysics, vol. 76, no. 2, pp. G37–G47, March 2011, doi: 10.1190/1.3548506.
 N. Diamanti and A. P. Annan, “Characterizing the energy distribution around GPR antennas,” Journal of Applied Geophysics, vol. 99, pp. 83–90, December 2013, doi: 10.1016/j.jappgeo.2013.08.001.
 C. Warren and A. Giannopoulos, “Experimental and Modeled Performance of a Ground Penetrating Radar Antenna in Lossy Dielectrics,” IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, vol. 9, no. 1, pp. 29–36, Jan. 2016, doi: 10.1109/JSTARS.2015.2430933.
 I. Giannakis, A. Giannopoulos, and C. Warren, “A Realistic FDTD Numerical Modeling Framework of Ground Penetrating Radar for Landmine Detection,” IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, vol. 9, no. 1, pp. 37–51, January 2016, doi: 10.1109/ JSTARS.2015.2468597.
 A. Benedetto, F. Tosti, L. Pajewski, F. D’Amico, and W. Kusayanagi, “FDTD Simulation of the GPR Signal for Effective Inspection of Pavement Damages,” Proceedings of the 15th International Conference on Ground Penetrating Radar (GPR 2014), Brussels, Belgium, 30 June – 4 July 2014, pp. 513–518, doi: 10.1109/ICGPR.2014.6970477.
 P. Shangguan and I. L. Al-Qadi, “Calibration of FDTD Simulation of GPR Signal for Asphalt Pavement Compaction Monitoring,” IEEE Transactions on Geoscience and Remote Sensing, vol. 53, no. 3, pp. 1538–1548, March 2015, doi: 10.1109/TGRS.2014.2344858.
 M. Solla, R. Asorey-Cacheda, X. Núñez-Nieto, and B. Conde-Carnero, “Evaluation of historical bridges through recreation of GPR models with the FDTD algorithm,” Construction and Building Materials, vol. 77, pp. 19–27, January 2016, doi: 10.1016/j.ndteint.2015.09.003.
 M. Loewer and J. Igel, “FDTD simulation of GPR with a realistic multi-pole debye description of lossy and dispersive media,” Proceedings of the 16th International Conference on Ground Penetrating Radar (GPR 2016), Hong Kong, 13– 6 June 2016, pp. 1–5, doi: 10.1109/ICGPR.2016.7572599.
 J. Igel, S. Stadler, and T. Günther, “High-resolution investigation of the capillary transition zone and its influence on GPR signatures,” Proceedings of the 16th International Conference on Ground Penetrating Radar (GPR 2016), Hong Kong, 13–16 June 2016, pp. 1–5, doi: 10.1109/ICGPR.2016.7572603.
 A. Benedetto, F. Tosti, L. Bianchini Ciampoli, A. Calvi, M. G. Brancadoro, and A. M. Alani, “Railway ballast condition assessment using ground-penetrating radar – An experimental, numerical simulation and modelling development,” Construction and Building Materials, vol. 140, pp. 508–520, June 2017, doi: 10.1016/j.conbuildmat.2017.02.110.
 T. Weiland, “A discretization model for the solution of maxwell’s equations for six-component fields,” Archiv Elektronik und Uebertragungstechnik, vol. 31, pp. 116–120, 1977.
 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.
 C. Warren, A. Giannopoulos, and I. Giannakis, “gprMax: Open source software to simulate electromagnetic wave propagation for Ground Penetrating Radar,” Computer Physics Communications, vol. 209, pp. 163–170, December 2016, doi: 10.1016/j.cpc.2016.08.020.
 C. Warren, A. Giannopoulos, N. Diamanti, and P. Annan, “An extension module to embed commercially sensitive antenna models in gprMax,” Proceedings of the 8th International Workshop on Advanced Ground Penetrating Radar (IWAGPR 2015), 7–10 July 2015, Florence, Italy, pp. 1–3, doi: 10.1109/IWAGPR.2015.7292623.
 C. Warren, L. Pajewski, A. Ventura, and A. Giannopoulos, “An Evaluation of Finite-Difference and Finite-Integration Time-Domain Modelling Tools for Ground Penetrating Radar Antennas,” Proceedings of the 10th European Conference on Antennas and Propagation (EuCAP 2016), 10–15 April 2016, Davos, Switzerland, pp. 1–5, doi: 10.1109/EuCAP.2016.7482010.
 X. Dérobert and L. Pajewski, “TU1208 Open Database of Radargrams: The Dataset of the IFSTTAR Geophysical Test Site,” Remote Sensing, vol. 10, article ID 530, pp. 1–50, March 2018, doi: 10.3390/rs10040530.
 L. Pajewski and A. Giannopoulos, “Electromagnetic Modelling of Ground Penetrating Radar Responses to Complex Targets,” Short Term Scientific Missions and Training Schools – Year 1, COST Action TU1208, L. Pajewski & M. Marciniak, Eds., Aracne Editrice, Rome, Italy, May 2014, ISBN 9788854872257, pp. 7–45 (available for download on www.gpradar.eu, more specifically here).
 L. Pajewski, F. Tosti, and W. Kusayanagi, “Antennas for GPR Systems,” Chapter 2 in A. Benedetto and L. Pajewski, Eds. “Civil Engineering Applications of Ground Penetrating Radar,” Publishing House: Springer International; Book Series "Springer Transactions in Civil and Environmental Engineering;" April 2015; e-book ISBN: 9783319048130; hardcover ISBN: 9783319048123; doi: 10.1007/9783319048130; 371 pp.
 F. Frezza, P. Martinelli, L. Pajewski, and G. Schettini, “A CWA-Based Detection Procedure of a Perfectly-Conducting Cylinder Buried in a Dielectric Half-Space,” Progress In Electromagnetics Research B, vol. 7, 265–280, 2008, doi: 10.2528/PIERB08032603.
 F. Frezza, P. Martinelli, L. Pajewski, and G. Schettini, “Short-Pulse Electromagnetic Scattering by Buried Perfectly Conducting Cylinders,” IEEE Geoscience and Remote Sensing Letters, vol. 4, no. 4, pp. 611–615, October 2007, doi: 10.1109/LGRS.2007.903078.
 A. De Coster and S. Lambot, “Full-wave removal of internal antenna effects and antenna-medium coupling for improved ground-penetrating radar,” IEEE Transactions on Geoscience and Remote Sensing, vol. 57, no. 1, pp. 93-103, January 2019, doi: 10.1109/TGRS.2018.2852486.
 A. De Coster and S. Lambot, “Fusion of Multifrequency GPR Data Freed From Antenna Effects,” in IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, vol. 11, no. 2, pp. 664-674, February 2018, doi: 10.1109/JSTARS.2018.2790419.
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Unrestricted use, distribution, and reproduction in any medium of this article is permitted, provided the original article is properly cited. Please cite this article as follows: A. Ventura and L. Pajewski, "Electromagnetic modelling and simulation of a high-frequency Ground Penetrating Radar antenna over a concrete cell with steel rods," Ground Penetrating Radar, Volume 1, Issue 2, Article ID GPR-1-2-3, July 2018, pp. 52-70, doi.org/10.26376/GPR2018009.
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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.