一层随机分布的异向材料小椭球粒子的极化散射特征

Polarimetric Scattering from a Layer of Random Metamaterial Small Spheroids

该文推导了异向材料(Metamaterial)小椭球粒子的复散射振幅函数。构造了一层随机取向的异向材料小椭球 粒子全极化散射的Mueller矩阵解。计算和比较了异向材料粒子和通常介质粒子的散射特性、同极化后向散射系数 σhh,σvv以及σhh-σvv随频率的变化。计算了任一椭圆极化入射下一层非均匀取向的随机分布异向材料粒子的同极 化和交叉极化后向散射系数,以及随机粒子产生散射场去极化的极化度。解释了异向材料的媒质参数对粒子散射特 性的影响和一层粒子的散射机理。结果表明:与通常介质粒子比较,异向材料粒子的散射产生了特征方向性的增强, 全极化散射呈现非对称模式,并且由于异向材料的ε和μ与频率的特殊关系,一层异向材料粒子的σhh-σvv随频率 有显著的复杂变化。

In this paper the complex scattering amplitude functions of a small metamaterial spheroid particle is derived. The Mueller matrix for polarimetric bistatic scattering from a layer of random metamaterial small spheroids, such as dishes or needles, is constructed. Bistatic scattering of metamaterial and dielectric spheroids are numerically calculated. Linearly co-polarized backscattering coefficients σhh, σvv and σhh-σvv are presented to show the dependence upon frequency. The co-polarized and cross-polarized backscattering coefficients and polarizability of a layer of non-uniformly oriented metamaterial spheroids under illumination of an elliptic polarized plane wave are numerically simulated. Effects of metamaterial parameters on scattering pattern and scattering mechanism are interpreted. Numerical results indicate that scattering of metamaterial particles is enhanced largely and appears apparent directivity. Meanwhile, polarized difference of σhh --σvv strongly varies with frequency due to constitutive dispersion of ε（w） and μ（w）.