大入射角情况下海面包含二面角反射器碎浪模型的电磁散射分析

Electromagnetic Scattering from Sea Surface with Dihedral Corner Model of Breaking Wave at Large Incident Angles

根据高分辨率雷达实测数据,在大入射角情况下,海面后向散射往往会出现强散射和大多普勒频移的现象,这些现象被认为是由波浪破碎引起的。在楔结构的基础上,本文提出了一个二面角反射器碎浪模型。运用物理光学法,对该模型进行电磁散射分析,结果表明,该模型可以体现水平极化的后向散射增强和高极化比现象。通过运用斜率判据,可以获得类似于真实海面情况的破碎点分布。结合双尺度方法,计算了包含碎浪模型的海面后向散射系数,结果表明该模型能够增强HH极化的散射强度,使其更符合实测数据,而对VV极化修正效果不明显。同时,考虑Bragg相速度,面元轨道运动和风驱漂流速度,计算了包含碎浪的海面多普勒谱,得到的结果也在也有很大的提高。

According to the high-resolution radar data,backscattering scattering of sea surfaces may give rise to phenomena of strong scattering and large Doppler offsets for HH polarization at large incident angles,which are usually considered to be caused by breaking waves.A new Dihedral Corner reflector model based on the Wedge of Lyzenga for breaking wave at LGA is proposed in this paper.Analyzed by the method of Physical Optics,this model can indicate the backscattering enhancement for HH component and the increment of polarization ratios.By using the slope criterion,the breaking points distribution which is similar with the real situation on the sea surface is obtained.The backscattering coefficients of sea surface with breaking wave are calculated by the two-scale method(TSM).The results indicate the breaking wave model can enhance the intensity of HH polarization,which is more agreeable with experimental data.For VV polarization,the revision fromthe breaking wave is not very obvious.At the same time,considering the Bragg phase velocity,orbital motion of facets and wind drift,the Doppler Spectrum of sea surface with breaking wave is simulated and a good improvement is obtained.