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Title: A metamaterial waveguide incorporating electric coupling for contactless data and power transfer
Author: Li, Yue
Awarding Body: University of Oxford
Current Institution: University of Oxford
Date of Award: 2015
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The background to this study is an effort to exploit a magneto-inductive waveguide (MIW) for near-field contactless data and power transfer applications. MIWs are almost purely magnetically coupled metamaterial waveguides whose coupling strengths can never exceed the limit of conservation of magnetic flux. This study raises the hypothesis that the coupling strength limit of MIWs can be overcome by incorporating additional electric coupling into the structures; therefore, more strongly coupled metamaterial waveguides can be built and serve as contactless near-field communication channels with wider passbands and lower attenuations. The hypothesis was tested in this study by investigating a new variant of the metamaterial waveguide: the Capacitor-Connected Grid (CCG), in which additional electric coupling is introduced by connecting coupling capacitors over inter-element gaps between conventional MIW metallic loop resonators. The study investigates the dispersion and attenuation characteristics of both one- (1-D) and two-dimensional (2-D) CCG devices, leading to a discussion on their potential uses in ultra- wideband (UWB) contactless near-field data transfer applications. A mixed coupling model calculating inter-element mixed coupling coefficients for arbitrarily configured CCG waveguides is derived based on the state-of-the-art, taking into account the shift of resonant frequency caused by electric coupling. The study also looks at terminal optimizations for 1-D CCG with a view to maximizing power transfer efficiency. A highlight of this study is that a 1-D CCG demonstration device in theory should be able to achieve 192.4% fractional bandwidth, which exceeds the 20% requirement of a UWB channel by a factor of 9.6, and is only 1/10 of the minimum attenuation of an equivalent-sized MIW device. Similar communication characteristics have also been found at selected transmission paths on a 2-D CCG demonstration structure. The results of this study on CCG waveguides verify the hypothesis that incorporating additional electric coupling into an almost purely magnetically coupled waveguide can improve its coupling strength and thereby achieve a communication channel with larger bandwidths and lower losses.
Supervisor: Stevens, Chris ; Edwards, David Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available