Numerical simulation of antenna transmission and reception for crosshole ground-penetrating radar

Geophysics ◽  
2006 ◽  
Vol 71 (2) ◽  
pp. K37-K45 ◽  
Author(s):  
James D. Irving ◽  
Rosemary J. Knight
Keyword(s):  
Ground Penetrating Radar ◽  
Heterogeneous Media ◽  
Numerical Models ◽  
Dipole Source ◽  
Computationally Efficient ◽  
Efficient Manner ◽  
Point Electric Dipole ◽  
Ground Penetrating ◽  
Difference Time ◽  
Current Behavior

Numerical models that account for realistic transmitter and receiver antenna behavior are necessary to develop waveform-based inversion methods for crosshole ground-penetrating radar (GPR) data. A challenge in developing such models is simulating the antennae in a computationally efficient manner so that inversions can be performed in a reasonable amount of time. We present an approach to efficiently simulate crosshole GPR transmission and reception in heterogeneous media. The core of our approach is a finite-difference time-domain (FDTD) solution of Maxwell's equations in 2D cylindrical coordinates. First, we determine the behavior of the current on a realistic GPR antenna in a borehole through detailed FDTD modeling of the antenna and its immediate surroundings. To model transmission and reception, we then replicate this antenna current behavior on a much-coarser grid using a superposition of point-electric-dipole source and receiver responses. Results obtained with our technique agree with analytical results, with numerical modeling results where the transmitter antenna and borehole are explicitly accounted for using a fine discretization, and with crosshole GPR field data.

scholarly journals Creating finite-difference time-domain models of commercial ground-penetrating radar antennas using Taguchi’s optimization method

Geophysics ◽  
2011 ◽  
Vol 76 (2) ◽  
pp. G37-G47 ◽  
Author(s):  
Craig Warren ◽  
Antonios Giannopoulos
Keyword(s):  
Finite Difference ◽  
Time Domain ◽  
Ground Penetrating Radar ◽  
Finite Difference Time Domain ◽  
Numerical Models ◽  
Optimization Method ◽  
Near Surface ◽  
Domain Models ◽  
Ground Penetrating ◽  
Difference Time

Very few researchers have developed numerical models of ground-penetrating radar (GPR) that include realistic descriptions of both the antennas and the subsurface. This is essential to be able to accurately predict responses from near-surface, near-field targets. We have developed a detailed 3D finite-difference time-domain models of two commercial GPR antennas — a Geophysical Survey Systems, Inc. (GSSI) 1.5-GHz antenna and a MALÅ Geoscience 1.2-GHz antenna — using simple analyses of the geometries and the main components of the antennas. Values for unknown parameters in the antenna models (due to commercial sensitivity) were estimated by using Taguchi’s optimization method, resulting in a good match between the real and modeled crosstalk responses in free space. Validation using a series of oil-in-water emulsions to simulate the electrical properties of real materials demonstrated that it was essential to accurately model the permittivity and dispersive conductivity. When accurate descriptions of the emulsions were combined with the antenna models, the simulated responses showed very good agreement with real data. This provides confidence for use of the antenna models in more advanced studies.

GPR attenuation and its numerical simulation in 2.5 dimensions

Geophysics ◽  
1997 ◽  
Vol 62 (2) ◽  
pp. 403-414 ◽  
Author(s):  
Tong Xu ◽  
George A. McMechan
Keyword(s):  
Time Domain ◽  
Ground Penetrating Radar ◽  
Finite Difference Time Domain ◽  
Superposition Method ◽  
Frequency Data ◽  
Buried Pipe ◽  
Ground Penetrating ◽  
Cole Model ◽  
Difference Time

Modeling of ground‐penetrating radar (GPR) data in 2.5 dimensions is implemented by superposition of 2-D finite‐difference, time‐domain solutions of Maxwell's equations for different horizontal wavenumbers. Dielectric, magnetic, and conductive losses are included in a single formulation. Attenuations associated with dielectric and magnetic relaxations are introduced by superposition of Debye functions at a set of relaxation frequencies and using memory variables to replace convolutions between the field variables and the decay functions. Better fits to data may always be obtained using the superposition method than by the Cole‐Cole model. Good fits to both loss‐tangent versus frequency data from lab measurements, and to 500 and 900 MHz field GPR profiles of a buried pipe and the surrounding layers, demonstrate the flexibility and viability of the modeling algorithm. Discrepancies between lab and in‐situ measurements may be attributed to scale differences and local variations that make lab samples less representative of the site than the GPR profile.

Non-Destructive Detection of Asphalt Concrete Stripping Damage using Ground Penetrating Radar

2021 ◽  
pp. 036119812110141
Author(s):  
Ye Ma ◽  
Mostafa A. Elseifi ◽  
Nirmal Dhakal ◽  
Mohammad Z. Bashar ◽  
Zhongjie Zhang
Keyword(s):  
Ground Penetrating Radar ◽  
Asphalt Concrete ◽  
Field Data ◽  
Visual Inspection ◽  
Asphalt Pavements ◽  
Reflected Waves ◽  
Ground Penetrating ◽  
The Relationship ◽  
Non Destructive ◽  
Difference Time

Ground penetrating radar (GPR) is a non-destructive evaluation technique, which has been applied to assess as-built pavement conditions and to evaluate damage and deterioration that develop over time. The objective of this study was to develop a methodology that uses GPR to detect moisture-related stripping damage in asphalt pavements. To achieve this objective, A Finite-Difference Time-Domain based simulation program was used to study the propagation of GPR signals in a stripped pavement. Field test data including GPR scans and visual inspection of cores of 202 pavement sections were used to study the relationship between GPR traces and asphalt concrete (AC) stripping damage. Based on this analysis, a novel GPR-based indicator, known as the accumulating in-layer peaks (AIP), was introduced to detect stripping damage in asphalt pavements. Field data and pavement cores were used to validate the proposed indicator and to evaluate its effectiveness in detecting the presence, extent, and severity of stripping in in-service pavement sections. Based on the results of the study, it was found that the presence of a void in the middle of the AC layer resulted in positive peaks in the reflected waves as indicated by the simulation of GPR signals. In addition, detected intermediate wave peaks between the surface and the interface between the AC and base layers on the GPR traces were associated with stripping damage in the AC layer. The AIP predicted accuracies for stripped and non-stripped sections were 80% and 96%, respectively, indicating its effectiveness in detecting stripping damage in flexible pavements.

Sign in / Sign up

Export Citation Format

Share Document