Electromagnetic Wave Manipulating Devices Designed By Transformation Optics

The transformation optics (TO) proposed by J. B. Pendry in 2006 has triggered great interest of applying it to various EM device designs due to its potential ability to arbitrarily manipulate the EM wave propagating with the pre-defined distribution of material constitutive parameters implemented through artificial metamaterials. More intensive theoretical and experimental explorations have brought in many interesting results and practical approaches. How to choose reasonably transformation function to design electromagnetic devices with practical feasibility, has become a problem we need to focus on.Based on such a background, this dissertation focuses on the designing of electromagnetic devices based on the transformation optics.These devices might find practical applications in retro-directive reflectors, parabolic antennas, new waveguides and some other fields.By employing linear coordinate transformations, we have designed two kinds of planar reflectors in this article. First, we present the design of a retro-directive reflector with dielectric cover on a planar conducting plane. The retro-directive reflector can be achieved with dielectric cover constructed with homogeneous birefringent dielectric medium, which reduces the complexity of practical realization. Such simple design allows us to further realize the retro-directive reflector by alternative layers of normal dielectrics based on the effective medium theory. The proposed design and a practical realization at microwave regime have been validated by full wave electromagnetic simulation, which demonstrates a broadband retro-directive response. We also present the design of a planar reflector with the performance of a parabolic reflector. It could transform a spherical wave generated by a point source placed in the focus into a plane wave propagating as a collimated beam along the axis. It is quite useful in antenna designs.Based on the conformal mapping method, we have designed an electromagnetic wave bend and a special waveguide in this dissertation. Only a few of the electromagnetic devices based on the transformation optics could be easily realized due to the complex requirements on material properties. To reduce material complexity, the conformal mapping method has been proposed. Conformal mapping can lead to much simpler material parameters for more practical implementation. Both an electromagnetic wave bend and a special waveguide we designed in this dissertation could be realized by isotropic dielectric materials.We have focused on the practical feasibility when designing electromagnetic devices based on the transformation optics. The methods proposed in this dissertation could be applied to design other electromagnetic devices based on TO. It could also be extended to other frequency bands such as terahertz frequencies and so on.