草原环境地表电磁散射的矩量法研究

Research on Electromagnetic Scattering from the Surface of Grassland Environment Using the Method of Moment

为了满足草原及其附近目标雷达探测和遥感的需要,选用高斯型分布表示草和土壤表面的高度起伏情况,选取Topp模型表示土壤层介电常数,采用双弥散模型表示草的介电常数,运用矩量法研究了草原环境地表的电磁散射特性,得到了散射系数的角分布曲线,讨论了入射角、入射波频率、草含水量、土壤湿度、土壤层和草层表面相关长度及均方根高度、草层厚度对散射系数的影响。结果表明,散射系数随散射角振荡地变化,在镜反射方向处有明显的散射增强效应;入射角和入射波频率对散射系数的影响较大,草含水量、土壤层和草层表面起伏相关长度和均方根高度对散射系数影响较小且较为复杂,土壤湿度、草层厚度对散射系数几乎没有影响。

In order to meet the needs of radar detection and remote sensing of grassland and nearby targets,Gaussian distribution is selected to represent the height fluctuations of grass and soil surface,Topp model is selected to represent the permittivity of the soil,and the double dispersion model is used to represent the permittivity of the grass layer,using the method of moments,the electromagnetic scattering characteristics of the surface of the grassland environment are studied,and the angular distribution curve of the scattering coefficient is obtained.The influence of the incident angle,incident wave frequency,grass water content,soil moisture,the root mean square and correlation length of surface height fluctuation of soil and grass layers and thickness of grass layer on the scattering coefficient is discussed.The results show that the scattering coefficient oscillates with the scattering angle,and there is an obvious scattering enhancement effect in the mirror reflection direction;the incident angle and the incident wave frequency have a greater influence on the scattering coefficient,grass water content,correlation length and root mean square height have little effect on the scattering coefficient and are more complicated,and the soil moisture and thickness of grass layer have almost no influence on the scattering coefficient.