雨介质中球形目标的GHz复合散射特性

将背景空间及其中存在的离散粒子作为一种连续的电介质,得出了背景空间中离散粒子存在时混合体的等效介电常量模型.利用该模型和国际电讯联盟给出的雨衰减测量数据,确定了GHz波段雨介质的等效介电常量并验证了其有效性.得出了雨环境中目标复合散射场的解析式,对雨环境中球形目标的复合微分散射进行了仿真与分析,进而研究了降雨率、电磁波频率及极化状态等因素对复合微分散射的影响.计算表明:降雨对微分散射的影响在10^-3分贝上,电磁波垂直极化时降雨的影响大于其水平极化时的影响.研究结果对精确制导和目标识别等有一定的参考意义.

Characteristics of Complex Scattering for a Medium Sphere in Rainfall in GHz Wave Band

The discrete particles and their existing space are supposed as a continuous medium, and its equivalent dielectric constant of the composite medium is developed. By using this constant and the attenuations induced by rainfall recommended by ITU, the dielectric constant is completely determined in GHz wave band and its validity is tested. The analytical expression of complex scattering field for a target in rainfall is presented. So the complex differential scattering in rainfall is simulated. The influences of rain, frequency and polarization etc on the scattering field are researched. Computations show that the influence induced by the rainfall on the differential scattering cross section is about 10^-3 dB, and the effect produced by the vertical polarization wave is bigger than that resulted by the parallel polarization wave. The obtained result provides a reference in precision guide and target identification.