GPR Modeling for Rapid Characterization of Layered Media

Abstract

Abstract-The success of a ground penetrating radar (GPR) signal modeling scheme largely depends on its accuracy and computational efficiency. Most of the modeling schemes suffer from inaccuracy because of unrealistic assumptions of complex GPR environment. In this respect full wave model (FWM) of GPR signal is a promising approach for accurate characterization of multi-layered media. However, large computation time of FWM compared to other simplified models makes the approach inefficient for real time application. In this work an FWM scheme is developed based on electric field equivalent magnetic current density at antenna phase center. The compact analytical expression of Green's function representing response due to layered media is derived. Then a plane wave model (PWM) is proposed by introducing a spreading factor based on simplified expression of the FWM. The model inversion is successfuly carried out by a gradient based algorithm. A stepped frequency continuous wave GPR in off-ground monostatic configuration is implemented in laboratory environment to verify performances of the models. Experimental analysis proves that the proposed PWM is as accurate as FWM, and its computation efficiency is enormous to detect layered media parameters.

Signal processing for coal layer thickness estimation using high‐resolution time delay estimation methods

“…where Here Ψ k = κ ρ 2 − κ k 2 is the vertical wavenumber of kth layer, κ k is the free space propagation constant, where κ k 2 = − ξ k η k , ξ k = jωμ k and η k = σ k + jωε k . Simplified expression for spectral domain Green's function by assuming TEM horn antenna as an infinitesimal x-directed electric diople, can be given by [35]…”

“…4.1.2 PWM: Implementation of FWM makes it difficult for realtime applications because of long computation time. To overcome this problem PWM of GPR signal based on common reflection method has been suggested by author [35]. The incorporation of spreading factor in PWM makes it accurate as FWM without changing its computational efficiency [35].…”

“…To overcome this problem PWM of GPR signal based on common reflection method has been suggested by author [35]. The incorporation of spreading factor in PWM makes it accurate as FWM without changing its computational efficiency [35]. Reflection coefficient r k, k + 1 for plane wave propagation at kth layer interface Z k is given by…”

“…However, for finite distance condition, modification is necessary in (23) to make it precise. In [35], Green's functions given by (15) and (19) are simplified and significant outcomes are utilised to develop the PWM by modifying the common reflection method. If we consider a two-layered media as half spaced air media followed by a medium having either thickness or conductivity is infinity, then spatial domain Green's function can be obtained from (15) and (19) as…”

“…Interestingly, for three-layered media, mth order reflections from interface Z 2 can be given as follows [35]:…”