基于变换光学的椭圆形透明聚集器的设计研究

基于麦克斯韦方程组在不同坐标系下具有形式不变性以及变换光学理论, 通过设计材料的本构参数(介电常数和磁导率)来引导电磁波的传播, 提出了具有电磁透明和电磁聚集两种功能的新型电磁器件-椭圆形透明聚集器的设计方法. 电磁波透明体不会阻挡电磁波的传播并且能够与斗篷内部进行交互; 电磁波聚集器是当电磁波入射到该装置上时, 电磁波能够被设计的装置按照要求集中到一个区域或者一个点, 实现电磁波能量的集中. 本文利用压缩变换和扩展变换推导出了这种电磁器件中各层的相对介电常数和相对磁导率的张量表达式, 并利用基于有限元算法的电磁仿真软件对该电磁器件进行了全波仿真验证, 得到了入射波从各个不同方向入射时磁场z 分量的分布图, 仿真结果证实了该设计方法和电磁参数的正确性. 最后还讨论了电磁器件存在损耗时的情况, 当损耗逐渐增大时, 器件的功能在一定程度上受到了削弱. 本文的设计方法为其他新型电磁器件的设计提供了一种新的思路.

Design and study of the elliptically cylindrical transparent concentrator based on transformation optics

The design of a novel elliptically cylindrical transparent concentrator with functions of both electromagnetic transparency and electromagnetic concentration is put forward based on the form invariance of Maxwell’s equations in different coordinate transformation and transformation optics theory, and through the design of material constitutive parameters (permittivity and permeability) to guide the electromagnetic wave propagation. The electromagnetic wave transparent body does not prevent the transmission of electromagnetic waves that can interact in the cloak. An electromagnetic wave concentrator is an electromagnetic device that controls the electromagnetic waves to focus on an area or at a point to realize the electromagnetic wave energy concentration according to the requirement when the electromagnetic waves are incident on the device. In this paper, the expressions of the relative permittivity and permeability tensors in every layer of the electromagnetic device are derived by compression transformation and extension transformation. Then full-wave simulations for the electromagnetic device are performed by using finite-element software. The distributions of z-component of the magnetic field for the electromagnetic waves incident from different directions are obtained. Simulation results confirm the validity of the design method and the constitutive parameter tensors. Finally, effect of electromagnetic loss on the performance of the device is also discussed. To a certain extent, the function of the device will be weakened when the electromagnetic loss increases gradually. The design method proposed in this paper provides a new approach that can be used to design other novel electromagnetic devices.