| dc.description.abstract | In this dissertation, the scattering properties for rough surface are introduced for both statistical and physical models. The statistical properties of rough surface scattering are studied by using NMM3D simulation data. A physical model of rough surface scattering names Advance Integral Equation Model (AIEM) is also investigated. To describe the complete scattering mechanism including single and multiple scattering, new expressions for multiple scattering are considered. The antenna pattern in the derivation of AIEM is also included for further achieving the truly measurements.
Firstly, the statistical properties of rough surface scattering are investigated by using NMM3D simulation data. We have performed simulations with the radar scattering matrix (coherence matrix) up to 958 independent realizations by using NMM3D model. The polarimetric speckle statistics (amplitude and phase difference) are then calculated based on the simulated scattering matrices, followed by the comparison with theoretical distributions. For fully developed speckle from the homogeneous rough surface, the results are examined and validated to ensure the simulated data quality is good in terms of polarimetric properties. The results show that the characterization of polarimetric descriptors for rough surface is well presented.
Next, the complete Kirchhoff field coefficient, complementary field coefficient and the traditional approximations of the Fresnel reflection coefficients are introduced in AIEM. The expressions for single scattering of AIEM are also derived. The comparisons of the bistatic scattering behavior by using the improved AIEM is in excellent agreement with numerical simulation and measured data, in terms of angular, frequency and polarization dependences. Based on this model, the transition model for AIEM is also proposed to improve the simulation accuracy. Validation by comparisons of the numerical method and experimental data gave good agreement.
Since the AIEM model has been developed to cover a wide range of surface roughness, it thus allows us to study the scattering properties of multiple terms in detail. The new expressions for multiple scattering of AIEM are derived. For easier explanation of the scattering mechanism, the new expressions include: upward and downward propagation waves in the medium 1 and 2 regions.
Finally, extension work to improve the model accuracy is reported in more detail. To consider the general bistatic scattering, antenna patterns of the transmitter and receiver are accounted for their variations of overlapping illuminated area covering the targets of interest when the bistatic scattering configurations are changed. For example, changing the incident angle and scattering angle, the common projected area is also changed. Hence, the scattering coefficient that is normalized by the illuminated area must be calculated accordingly.
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