Cataloged from PDF version of article.The finite-difference time-domain (FDTD) method\ud
is used to simulate three-dimensional (3-D) geometries of realistic\ud
ground-penetrating radar (GPR) scenarios. The radar unit is modeled\ud
with two transmitters and a receiver in order to cancel the\ud
direct signals emitted by the two transmitters at the receiver. The\ud
transmitting and receiving antennas are allowed to have arbitrary\ud
polarizations. Single or multiple dielectric and conducting buried\ud
targets are simulated. The buried objects are modeled as rectangular\ud
prisms and cylindrical disks. Perfectly-matched layer absorbing\ud
boundary conditions are adapted and used to terminate the\ud
FDTD computational domain, which contains a layered medium\ud
due to the ground–air interface
The versatility of the three-dimensional (3-D) finite-difference time-domain (FDTD) method to model arbitrarily inhomogeneous geometries is exploited to simulate realistic groundpenetrating radar (GPR) scenarios for the purpose of assisting the subsequent designs of high-performance GPR hardware and software. The buried targets are modeled by conducting and dielectric prisms and disks. The ground model is implemented as lossy with surface roughness, and containing numerous inhomogeneities of arbitrary permittivities, conductivities, sizes, and locations. The impact of such an inhomogeneous ground model on the GPR signal is demonstrated. A simple detection algorithm is introduced and used to process these GPR signals. In addition to the transmitting and receiving antennas, the GPR unit is modeled with conducting and absorbing shield walls, which are employed to reduce the direct coupling to the receiver. Perfectly matched layer absorbing boundary condition is used for both simulating the physical absorbers inside the FDTD computational domain and terminating the lossy and layered background medium at the borders
Cataloged from PDF version of article.An efficient technique to improve the accuracy\ud
of the finite-difference time-domain (FDTD) solutions employing\ud
incident-wave excitations is developed. In the separate-field\ud
formulation of the FDTD method, any incident wave may be\ud
efficiently introduced to the three-dimensional (3-D) computational\ud
domain by interpolating from a one-dimensional (1-D)\ud
incident-field array (IFA), which is a 1-D FDTD grid simulating\ud
the propagation of the incident wave. By considering the FDTD\ud
computational domain as a sampled system and the interpolation\ud
operation as a decimation process, signal-processing techniques\ud
are used to identify and ameliorate the errors due to aliasing.\ud
The reduction in the error is demonstrated for various cases. This\ud
technique can be used for the excitation of the FDTD grid by any\ud
incident wave. A fast technique is used to extract the amplitude\ud
and the phase of a sampled sinusoidal signal
The relative accuracies and efficiencies of these two excitation schemes are compared, and it has been shown that higher-order interpolation techniques can be used to improve the accuracy of the IFA scheme, which is already quite efficient.
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