采用时域有限差分法研究了多因素对光学介质薄膜表面冗余节瘤粒子微分散射截面随散射角的变化规律.对光学介质薄膜表面冗余节瘤粒子复合散射进行建模,并针对典型半空间问题,对总散射场进行分解并对相应的场相位进行求解,给出网格剖分规...采用时域有限差分法研究了多因素对光学介质薄膜表面冗余节瘤粒子微分散射截面随散射角的变化规律.对光学介质薄膜表面冗余节瘤粒子复合散射进行建模,并针对典型半空间问题,对总散射场进行分解并对相应的场相位进行求解,给出网格剖分规则.将数值结果退化为冗余球体粒子,与MOM (Method of Moments)矩量法进行详细比较,验证程序的有效性.分析P偏振光入射下,入射角、长短轴轴比和镶嵌高度h对Cu和SiO_2镶嵌粒子微分散射截面随散射角的影响规律.结果表明:微分散射截面的最大峰值出现在入射角的镜面值角度;在镜向散射区域附近,对于扁平回转椭球体粒子微分散射截面随冗余节瘤粒子轴比的增大而减小,扁长回转椭球粒子的规律相反;在[-90°,-60°]散射角区域,微分散射截面与冗余节瘤粒子镶嵌高度成正比,镶嵌高度对介质粒子散射特性影响更大.展开更多
In the process of atmospheric refractivity estimation from radar sea echo,the objective function that calculates the match between the predicted and observed field plays an important role.To reduce the effect of noise...In the process of atmospheric refractivity estimation from radar sea echo,the objective function that calculates the match between the predicted and observed field plays an important role.To reduce the effect of noises from long ranges on the objective function,we present a selection method of final ranges for inversion.An adaptive objective function is introduced with a linear distance weight added to the least squares error function(LSEF).Through an evaporation duct height(EDH)retrieving process,the performance of the adaptive objective function is evaluated.The result illustrates that the present method performs better than the LSEF in EDH inversions from clutters with different clutter-to-noise ratios.展开更多
Based on the impedance/admittance rough boundaries, the reflection coefficients and the scattering cross section with low grazing angle incidence are obtained for both VV and HH polarizations. The error of the classic...Based on the impedance/admittance rough boundaries, the reflection coefficients and the scattering cross section with low grazing angle incidence are obtained for both VV and HH polarizations. The error of the classical perturbation method at grazing angle is overcome for the vertical polarization at a rough Neumann boundary of infinite extent. The derivation of the formulae and the numerical results show that the backscattering cross section depends on the grazing angle to the fourth power for both Neumann and Dirichlet boundary conditions with low grazing angle incidence. Our results can reduce to that of the classical small perturbation method by neglecting the Neumann and Dirichlet boundary conditions.展开更多
A modified perturbation method of electromagnetic scattering from a rough surface is presented,in which the effect of the curvature of the surface is taken into account based on the conventional small perturbation met...A modified perturbation method of electromagnetic scattering from a rough surface is presented,in which the effect of the curvature of the surface is taken into account based on the conventional small perturbation method.The problem of scattering error by the conventional small perturbation method at grazing angle is solved.Compared with a set of measured data,the numerical results of the backscattering radar cross section show that this modified perturbation method is validity for small,moderate and grazing angle incidence.展开更多
The general expression of the fractal linear array factors is derived.The similarity of the patterns and their fractal features are examined.The relation between the maximum side-lobe and the fractal dimension is shown.
With the theory of rough surfaces scattering,a numerical formula for calculating the bistatic and backscattering radar cross section from randomly dielectric rough surfaces is derived by using phase-perturbation techn...With the theory of rough surfaces scattering,a numerical formula for calculating the bistatic and backscattering radar cross section from randomly dielectric rough surfaces is derived by using phase-perturbation technique.The backscattering laser radar cross sections per unit of some rough samples are computed at λ=1.06μm.The numerical results are in good agreement with experimental data.展开更多
文摘采用时域有限差分法研究了多因素对光学介质薄膜表面冗余节瘤粒子微分散射截面随散射角的变化规律.对光学介质薄膜表面冗余节瘤粒子复合散射进行建模,并针对典型半空间问题,对总散射场进行分解并对相应的场相位进行求解,给出网格剖分规则.将数值结果退化为冗余球体粒子,与MOM (Method of Moments)矩量法进行详细比较,验证程序的有效性.分析P偏振光入射下,入射角、长短轴轴比和镶嵌高度h对Cu和SiO_2镶嵌粒子微分散射截面随散射角的影响规律.结果表明:微分散射截面的最大峰值出现在入射角的镜面值角度;在镜向散射区域附近,对于扁平回转椭球体粒子微分散射截面随冗余节瘤粒子轴比的增大而减小,扁长回转椭球粒子的规律相反;在[-90°,-60°]散射角区域,微分散射截面与冗余节瘤粒子镶嵌高度成正比,镶嵌高度对介质粒子散射特性影响更大.
基金Supported by the National Natural Science Foundation of China under Grant No 60771038.
文摘In the process of atmospheric refractivity estimation from radar sea echo,the objective function that calculates the match between the predicted and observed field plays an important role.To reduce the effect of noises from long ranges on the objective function,we present a selection method of final ranges for inversion.An adaptive objective function is introduced with a linear distance weight added to the least squares error function(LSEF).Through an evaporation duct height(EDH)retrieving process,the performance of the adaptive objective function is evaluated.The result illustrates that the present method performs better than the LSEF in EDH inversions from clutters with different clutter-to-noise ratios.
文摘Based on the impedance/admittance rough boundaries, the reflection coefficients and the scattering cross section with low grazing angle incidence are obtained for both VV and HH polarizations. The error of the classical perturbation method at grazing angle is overcome for the vertical polarization at a rough Neumann boundary of infinite extent. The derivation of the formulae and the numerical results show that the backscattering cross section depends on the grazing angle to the fourth power for both Neumann and Dirichlet boundary conditions with low grazing angle incidence. Our results can reduce to that of the classical small perturbation method by neglecting the Neumann and Dirichlet boundary conditions.
基金Supported by the Teaching and Research Award Program for Outstanding Young Teachers in Higher Education Institutions of the Ministry of Education,P.R.China.
文摘A modified perturbation method of electromagnetic scattering from a rough surface is presented,in which the effect of the curvature of the surface is taken into account based on the conventional small perturbation method.The problem of scattering error by the conventional small perturbation method at grazing angle is solved.Compared with a set of measured data,the numerical results of the backscattering radar cross section show that this modified perturbation method is validity for small,moderate and grazing angle incidence.
文摘The general expression of the fractal linear array factors is derived.The similarity of the patterns and their fractal features are examined.The relation between the maximum side-lobe and the fractal dimension is shown.
文摘With the theory of rough surfaces scattering,a numerical formula for calculating the bistatic and backscattering radar cross section from randomly dielectric rough surfaces is derived by using phase-perturbation technique.The backscattering laser radar cross sections per unit of some rough samples are computed at λ=1.06μm.The numerical results are in good agreement with experimental data.