Department of Electrical, Electronics and Computer Engineering (DIEEI), University of Catania, Viale A. Doria 6, 95126, Catania, Italy.
Department of Information Engineering, Infrastructures and Sustainable Energy (DIIES), University "Mediterranea" di Reggio Calabria, Via Graziella, Loc. Feo di Vito, 89100, Reggio Calabria, Italy.
Sci Rep. 2017 Jun 16;7(1):3680. doi: 10.1038/s41598-017-03749-y.
The synthesis of non-magnetic 2D dielectric cloaks as proper solutions of an inverse scattering problem is addressed in this paper. Adopting the relevant integral formulation governing the scattering phenomena, analytic and numerical approaches are exploited to provide new insights on how frequency and direction of arrival of the incoming wave may influence the cloaking mechanism in terms of permittivity distribution within the cover region. In quasi-static (subwavelength) regime a solution is analytically derived in terms of homogeneous artificial dielectric cover with ε < ε , which is found to be a necessary and sufficient condition for achieving omnidirectional cloaking. On the other hand, beyond quasi-static regime, the cloaking problem is addressed as an optimization task looking for only natural dielectric coatings with ε > ε able to hide the object for a given number of directions of the incident field. Simulated results confirm the validity of both analytic and numerical methodologies and allow to estimate effective bandwidths both in terms of frequency range and direction of arrival of the impinging field.
本文研究了将非磁性二维介电 cloak 作为逆散射问题的适当解进行合成的问题。采用控制散射现象的相关积分公式，利用解析和数值方法深入了解入射波的频率和到达方向如何影响覆盖区域内介电常数分布的 cloak 机制。在准静态（亚波长）情况下，以ε<ε的均匀人工介电覆盖层为基础，从解析角度推导出了一个解，这被发现是实现全向 cloak 的必要和充分条件。另一方面，在准静态范围之外， cloak 问题被视为一个优化任务，寻找仅具有ε>ε的天然介电涂层，以便在给定数量的入射场方向下隐藏物体。模拟结果验证了分析和数值方法的有效性，并允许根据入射场的频率范围和到达方向来估计有效带宽。
