Evaluation of far-field layered media modeling for time-domain commercial GPR antenna

The possibility to estimate accurately the subsurface electromagnetic properties from commercial ground penetrating radar (GPR) signals using inverse modeling is obstructed by the appropriateness of the forward model describing the GPR subsurface system. In 2004 Lambot et al. proposed a promising GPR model for multilayered media characterization based on frequency-domain subsurface Green´s functions and antenna effects filtering by linear transfer functions. In this study we analyzed the feasibility of full-waveform frequency-domain modeling for off-ground time-domain commercial GPR. We calculated the antenna transfer functions using measurements with a 1 GHz center frequency transmitting and receiving horn antenna situated at different heights above a copper plane. Also we validated the approach in the laboratory with measurements performed over the water as a homogeneous medium with frequency dependent electrical properties. A single Debye relaxation model was used to describe the frequency dependent water electrical properties with correcting the relaxation period and static dielectric permittivity of water for temperature. Inversion of the radar data in the frequency-domain provided relatively accurate estimations of the antenna heights and water layer thickness. These results demonstrated the ability of full-waveform modeling to be also used for commercial time-domain radars.