Advances in Emerging Electromagnetics Topics: Metamaterials and Wireless Power Transfer.

electromagnetics;metamaterials;wireless power;Electrical Engineering;Engineering;Electrical Engineering

Tierney, Brian BenjaminMichielssen, Eric ;

University of Michigan

关键词: electromagnetics;    metamaterials;    wireless power;    Electrical Engineering;    Engineering;    Electrical Engineering;   

Others  :  https://deepblue.lib.umich.edu/bitstream/handle/2027.42/133260/btierney_1.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Since their introduction 15 years ago, metamaterials have enabled the design of various new and exotic electromagnetic devices. These devices have included polarization convertors, beam refractors, absorbers, wave collimators, and many others. However, unlocking the full potential of metamaterials requires improving existing design methods. For example, one popular design approach has been transformation electromagnetics, which exploits the form invariance of Maxwell’s equations under coordinate transformations. However, transformation techniques can often yield material parameters which are difficult to implement, e.g. highly-anisotropic or inherently-dispersive materials.In this thesis, new techniques are proposed and demonstrated to overcome the deficiencies of current metamaterial design methods. Specifically, a new technique is developed to generate arbitrary radiation patterns using metamaterial leaky-wave antennas. The featured synthesis method is an improvement over the commonly used ray optics method, which often results in degradation of the radiation pattern. The technique is demonstrated using a new leaky-wave impedance-surface topology that is advantageous due to its independent control of the leakage rate, phase progression, and polarization of leaky-wave modes as well as its simple, planar fabrication. Furthermore, an optimization technique is developed to overcome the deficiencies of coordinate-transformation methods used to design exotic electromagnetic devices. The proposed procedure has two primary advantages over coordinate-transformation methods: (1) it can place constraints on material parameters to improve practicality and bandwidth and (2) it permits the design of devices for which a transformation map may be difficult/impossible to find, such as those with a different prescribed output for each stipulated input. The procedure is used to design a beamformer with 7 prescribed input/output combinations.In addition to metamaterial topics, this thesis also presents the design of a wireless non-radiative power transfer (WNPT) system that employs novel, compact, planar-loop resonators with integrated transmission lines and capacitive stubs. These high-Q resonators offer excellent coil-to-coil efficiencies and can be easily fabricated using standard printed-circuit board processes. Moreover, it is shown that the parameters of the resonator can be tailored to achieve a conjugate impedance-matched condition at a prescribed coupling distance, thereby eliminating the need for external matching networks used previously in the literature.