各向异性人工材料的电磁波吸收特性

利用传输矩阵法研究了含各向异性人工材料的一维结构的电磁波吸收特性,分析了入射波频率、极化方向、入射角以及材料厚度对电磁波吸收率的影响.结果表明,电磁波垂直入射到单层各向异性人工材料中,尽管s波和p波的吸收率极大值出现在不同的频率,但两种波的吸收率随层厚增大的变化规律一致.斜入射时,不管入射角如何变化,s波和p波的吸收率都随着层厚的增大而趋于定值,该极限值由入射角决定.改变入射波频率,当某一频率对应磁导率张量的矩阵元的实部为负值,对应极化波的吸收率随层厚的增大而趋于定值;当磁导率张量的矩阵元的实部为正值,对应极化波的吸收率随层厚的增大而振荡,且峰值出现在层厚为λ/2的整数倍时.含各向异性人工材料的三层结构的吸收率优于单层结构.以上结论可为使用各向异性人工材料制作电磁波吸收器提供理论支持.

Electromagnetic Wave Absorption Properties of Anisotropic Metamaterial

The electromagnetic wave absorption properties of one dimensional anisotropic metamaterial have been studied by the transfer matrix method.The absorbance relies on the frequency of the incident wave,polarization direction,the incident angle and the thickness of the metamaterial.The results show that the maximum value of the absorbance for s-polarized wave and p-polarized wave appears at different frequencies for normal incidence on a single anisotropic metamaterial plate.The absorbance for both s-polarized wave and p-polarized wave shows the same variation trend with the increasing of the thickness.For oblique incidence with the arbitrary incident angle,the absorbance for both s-polarized wave and p-polarized wave tends to be a constant as the thickness increases.The limitation value is determined by the incident angle.If the matrix element of the permeability tensor is negative for a certain frequency,the absorbance of the corresponding polarized wave will tend to be a constant with the increasing of the thickness.If the matrix element of the permeability is positive,the absorbance of the corresponding polarized wave will be oscillating when the thickness increases.The absorbance has the maximal value if the thickness equals to the integer multiple ofλ/2.The three layer system show better results than the single layer system.The above conclusions may give the theory support for the anisotropic metamaterial to realize the electromagnetic wave absorber.