A compact UWB bowtie-slot antenna (36×23 cm2) fed by a CPW transition is proposed for an improved ground-coupling radar. The antenna has an operating frequency band in the range [0.46 ; 4] GHz. Full-wave modeling using the FDTD approach has allowed to study in details the antenna radiation characteristics in air and in the presence of a soil. Afterwards, a radar system made of a pair of independent shielded bowtie antennas has been considered to probe the sub-surface very close to the air-soil interface. The polarization diversity in the E and H-planes is an important aspect which has been studied in order to further detect the orientation of damages (cracks, delaminations…) in civil engineering structures. Measurements in a dry and wet sand in different system configurations have allowed to first characterize the GPR system and to draw comparisons with numerical results. The ability of the radar to detect small buried objects is investigated.
2. Yelf, R. J., "Application of ground penetrating radar to civil and geotechnical engineering Electromagnetic Phenomena,", Vol. 7, No. 1, 102-117, 2007.
3. Diamanti, N. and D. Redman, "Field observations and numerical models of GPR response from vertical pavement cracks," J. Applied Geophysics, Vol. 81, 106-116, 2012.
doi:10.1016/j.jappgeo.2011.09.006
4. Becker, J., D. Filipovic, H. Schantz, and S.-Y. Suh, "Ultra-wideband antennas," International Journal of Antennas and Propagation, Special Issue, Hindawi Publishing, 2008.
5. Wiesbeck, W., G. Adamiuk, and C. Sturm, "Basic properties and design principles of UWB antennas," Proceedings of the IEEE, Vol. 97, No. 2, 372-385, Feb. 2009.
doi:10.1109/JPROC.2008.2008838
6. Rahel, K., S. Bashir, and N. Fazal, "Review of techniques for designing printed antennas for UWB application," International Journal of Sciences & Emerging Technologies, Vol. 1, No. 2, 48-60, Feb. 2012.
7. Zheng, G., A. A. Kishk, A. W. Glisson, and A. B. Yakovlev, "Slot antenna fed by a CPW line with tapered transition," Microwave and Opt. Technol. Letters, Vol. 38, No. 6, 465-467, Sep. 2003.
doi:10.1002/mop.11091
8. Wu, C.-J., I.-F. Chen, and C.-M. Peng, "A dual polarization bow-tie slot antenna for broad band communications," PIERS Proceedings, 217-221, Marrakesh, Marocco, Mar. 20-23, 2011.
9. Atteia, G. E. and A. A. Shaalan, "Wideband partially-covered bowtie antenna for ground-penetrating radars," Progress In Electromagnetics Research, Vol. 71, 211-226, 20072007.
10. Yilmaz, O., Seismic Data Analysis: Processing, Inversion, and Interpretation of Seismic Data: Volume 1, SEG Books, 2001.
11. Hamann, G. and J. Tronicke, "Assessing uncertainties in determining GPR ground wave velocities: An approach based on spectral velocity analysis," 6th International Workshop of Advanced Ground Penetrating Radar (IWAGPR), 1-5, Aachen, 2011.
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