Utilities detection through the sum of orthogonal polarization in 3D georadar surveys

Abstract

Ground penetrating radar (GPR) is widely used in subsurface investigations for extracting the position and the route followed by the utility, an issue that gains more and more importance when considering the cost related to trench damage and disruptions. However, it has been noted that various targets of GPR surveys, especially linear and elongated targets, have polarization‐dependent scattering characteristics. This implies that the visibility of a subsurface scatterer in the acquired data depends on the used antenna configuration and its orientation with respect to the feature to be imaged. Furthermore, wave attributes could be modified by the surrounding soil anisotropy and heterogeneity degree. As the GPR antennas are composed of directional dipoles, any changes in the propagation plane of the returning wave affects the recording of GPR data. This work presents an approach based on a combination of mutually orthogonal GPR 3D data volumes through which polarization issues can be overcome, ensuring target detection even when the position and material are adverse. The strategy is evaluated through two field examples: in homogeneous soil this technique fully recovers the polarization mismatch, providing results that are closely similar to the ones that would be obtained with the optimal configuration; in heterogeneous environments it overcomes the wavelet alteration, depolarization included, strongly enhancing the signal to noise ratio and improving target reconstruction.

Sparse Ground Penetrating Radar Acquisition: Implication for Buried Landmine Localization and Reconstruction

“…Although the significant advantages of 3-D surveying strategies are well documented, they generally require much greater acquisition expenditure and effort than that of traditional sparse bidimensional acquisitions. The 3-D imaging improvements with GPR have been tested in most domains of shallow subsurface disciplines, from civil engineering to agriculture and archeology [6]- [8].…”

Dependence of landmine radar signature on aspect angle

“…The use of multiple polarisations can provide key additional information [25,26], because the response of each polarisation is highly correlated to the landmine geometrical structure as well as to its physical properties [27,28]. For example, multiple polarisations have been successfully used to identify different types of targets, such as cables and utilities [29][30][31], thanks to their explicit polarimetric behaviour, but also to correctly reconstruct complex environments [32,33]. On the whole, polarisation is supposed and expected to improve the characterisation of the acquired subsurface [34,35].…”

Bistatic radar signature of buried landmines

“…GPR operates by transmitting an electromagnetic signal into the subsurface and detecting a target echo at a receiver antenna, that is reflected due to the dielectric discontinuity between the target and the propagation medium. GPR has a wide range of applications in archaeology [9], [10], engineering [11], [12] [13] and geological applications [14], [15]. One of the problems with GPR for landmine detection is that dielectric discontinuities occur at places other than the mine, such as roots, rocks and hollows, as well as other battlefield debris.…”