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Title: All dielectric composites for metamaterial applications
Author: Lei, Qin
ISNI:       0000 0004 6346 6246
Awarding Body: University of Oxford
Current Institution: University of Oxford
Date of Award: 2015
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This thesis describes my work on manufacturing of all dielectric polymer/ceramic composites for electromagnetic property customisation at microwave frequencies. Electromagnetic wave manipulation can be achieved with the help of transformation optics concept and metamaterials with desired permittivity and permeability properties. The use of all-dielectric metamaterials, in particular, offers a novel solution to broadband, low loss microwave devices. In this work, polymer/ceramic composites were studied to provide materials with a wide range of permittivity that can be customised precisely by optimised manufacturing routes. Thermoplastic perfluoroalkoxy (PFA) and thermoset epoxy were mainly used as polymer matrices and ferroelectric powders such as barium titanate used as ceramic fillers. Different composite types were fabricated by spraying, casting and 3D printing, with each manufacturing method carefully studied to produce stable and uniform composite quality. The microstrcutures of these composites were examined by microtomy and SEM and the dielectric properties were assessed by impedance and waveguide measurements for difference microwave frequency ranges. Controllable dielectric constants from 3 to 18 with high accuracy in epoxy/BT composites were achieved at 12 - 18 GHz. These composites were then used to fabricate advanced microwave devices such as the power divider lens to demonstrate my capability of permittivity customisation. Simulations for these advanced applications were done in Comsol Multiphysics and were compared to the experimental results.
Supervisor: Grovenor, Chris ; Grant, Patrick Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available