A practical approach is proposed and used to investigate the electromagnetic (EM) signature of barefaced terrain using 3D computer electromagnetic models (CEM). Six barefaced terrain types with different electrical, physical and chemical properties were investigated. They comprise homogeneous and heterogeneous terrain. The approach developed CEMs in software using refl ectance spectroscopy and dielectric permittivity data. EM signature models of the barefaced terrain are based on fi nite integration technique (FIT) solvers. The developed technique and models are valid for diverse materials under test including unconventional petroleum resources like shale rock and oil sands. The remote sensing of terrain from airborne or satellite synthetic aperture radar requires a prior determination of the EM signature for accurate classifi cation. The implementation of our new method combined empirical measurements and FIT in three steps. Geochemical properties determined using refl ectance spectroscopy in the mid-infrared region (2.5-25 µm) identifi ed the presence of bitumen, clay and moisture in Nigerian oil sands while reststrahlen effects were observed in beach sand compared with gravel and pebble. Also new information on both real, e′ r and imaginary, e′ r permittivity of terrain was experimentally obtained for frequency varying from 1 to 11 GHz. After post-processing, the results differed from expectation of complex refractive index method for petrophysics although adequate Kramers-Krönig correlation between measured real, e′ r and imaginary, e′ r permittivity data was exhibited. Our approach uses the results to improve the CEMs for superior EM signature determination. An application of our new technique to land degradation monitoring using radar is also presented.
Accurate characterisation of oil sand terrain using airborne or satellite synthetic aperture radar (SAR) requires prior determination of the radar signature of the terrain. Here we investigate the SAR signature of Agbabu oil sands. Firstly, the chemical characteristics of two strains of Agbabu oil sand samples are determined using Fourier Transform Infrared (FTIR) spectroscopy in the nearinfrared (NIR) and mid-infrared (MIR) regions (2.5-25µm). Spectroscopic results of both hard oil sand (HOS) and viscous oil sand (VOS) are positive when compared to common soil and oil sands from Canada. Thereafter, the electrical properties of Agbabu oil sands are experimentally determined using a coaxial probe technique for frequency varying from 1-8.5 GHz. The results provide new information on the complex electrical permittivity *(ω) and loss tangent, tan δ which exhibit an adequate Kramers-Krönig correlation between real and imaginary permittivity for both VOS and HOS. Finally, the results from the experiments are used to create computer simulation models to determine the SAR radar signature of Agbabu oil sands which is then compared to other materials such as iron and steel at L-, C-and X-band frequencies. The model parameters include look angle θ l = 20° to 90°, measured dielectric constant and surface roughness ks.
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