分形海面的微波电磁散射计算模型

利用2维Weierstrass带限函数建立了模拟粗糙海面形状的模型,讨论了分形维数、频率幅度尺度因子等分形参数对海面形状的影响。以粗糙海面形状模型为基础,针对模拟的分形海面形状,从亥姆霍兹积分出发,利用基尔霍夫近似推导出2维分形海面的电磁散射系数,并进行了数值模拟。对微波电磁散射特性随分形维数、频率幅度尺度因子、入射波入射角变化的规律做了进一步讨论分析。在低掠射角时电波会受海面的遮挡,用遮挡函数对散射系数进行修正。研究表明:随着分形维数的增大,散射峰分布变均匀。频率幅度尺度因子越大,散射也越分散。随着入射角的增大,后向散射也逐渐增强,而前向散射逐渐减弱。

Model of microwave electromagnetic scattering at fractal sea surface

Based on the 2D band-limited Weierstrass function, the model of the rough sea surface is developed, and the effects of the fractal dimension, the frequency and amplitude factor are discussed. Considering the simulated fractal surface, the analytic expression of scattering coefficient is deduced based on Helmholtz integral and Kirchhoff approximation. The shadow function is used to amend the scattering coefficient at low grazing angle when microwaves are shaded by the rough sea surface. The effects of the fractal dimension, the frequency and amplitude factor and the incidence angle on the electromagnetic scattering are discussed. The peaks of scattering coefficient are more uniformly distributed with the increasing of the fractal dimension or the frequency and amplitude factor. The back sca