复杂的二维海面电磁散射模型

A model of electromagnetic scattering in a 2-D dimensional complex sea surface

根据描述海面几何特性的Weierstrass分形函数模型,结合海水的介电特性,建立了复杂的二维海面电磁散射模型.该模型中,在传统的分形模型基础之上,将海水的介电常数看做海水盐度和温度的函数,推导出了海面的后向散射系数在入射波处于水平和垂直2种极化状态下的表达式.然后,在不同的频段下对海水的介电常数进行了分类讨论,得到了其在3个不同频段里的近似表达式,有助于实际电磁散射计算中的简化.最后,将模型的计算结果与传统的DV模型和测试的结果做了比较,发现该模型的结果比传统的DV模型的更接近于测试结果,误差仅约2 dB左右.因此,利用这一模型,可以得到较为全面而准确的海面散射系数.

Using the band-limited Weierstrass fractal model that describes geometrical characteristic of the sea surface and the permittivity characteristics of sea water, a complex model of electromagnetic scattering for 2-D complicated sea surfaces was developed. In this model, based on the traditional fractal model, the permittivity of sea water was regarded as functions of temperature and salinity. Then two analytic expressions of the backscattering coefficients of sea water were derived in horizontal and vertical polarized states respectively. Both the fractal geometrical characteristic and permittivity of sea water in various frequency bands were then analyzed in detail, and their approximate expressions were obtained in three bands, which simplifies the calculations of actual electromagnetic scattering. Finally, the proposed system was compared with the conventional DV model and experimental results. The results of this model were within 2 dB error, and obviously much closer to experimental results than those from the traditional DV model. Therefore, it is suggested that using this model can provide us a whole and comparatively exact electromagnetic scattering coefficients of sea surface.