An electromagnetic characterization of a bianisotropic medium based on nonlocal homogenization theory with small positional disorders has been presented. The proposed theory is general and can be used for any type of random positional disorders provided that the probability density functions associated with these positional disorders are known. Later, the proposed general theory was used for a nonlocal metamaterial composed of coated spheres with Gaussian types of positional disorder in the microwave and infrared range of frequencies. It is studied that by increasing the positional disorder, the epsilon negative, mu negative and double negative bandwidths of a metamaterial reduce and even vanish for some special cases. It is found that the bandwidths of absorption peaks associated with the imaginary parts of effective permittivity and effective permeability become wider with the increase in positional disorder. It is also concluded that magnetoelectric coupling arising due to lattice effects become almost negligible for the relatively large positional disorder for a weak nonlocal or spatially dispersive metamaterial. The proposed findings are helpful in the designing of nonlocal disordered metamaterials.

中文翻译：

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位置紊乱对涂层球体超材料非局部有效参数的影响

提出了基于具有小位置紊乱的非局域均匀化理论的双各向异性介质的电磁表征。所提出的理论是通用的，并且可以用于任何类型的随机位置障碍，前提是与这些位置障碍相关的概率密度函数是已知的。后来，所提出的一般理论被用于由在微波和红外频率范围内具有高斯类型位置无序的涂层球体组成的非局域超材料。研究表明，通过增加位置紊乱，超材料的ε负、μ负和双负带宽会减小，在某些特殊情况下甚至消失。研究发现，随着位置紊乱的增加，与有效介电常数和有效磁导率的虚部相关的吸收峰的带宽变得更宽。还得出结论，对于弱非局域或空间色散超材料而言，由于晶格效应而产生的磁电耦合对于相对较大的位置紊乱几乎可以忽略不计。所提出的发现有助于非局部无序超材料的设计。