| dc.description.abstract | This thesis explores advanced methods for controlling and manipulating the radiative behaviour of microwave sources through strategic environmental design. By integrating the theoretical foundations of electromagnetism with sophisticated modelling and experimental techniques, this research demonstrates how minor changes in the local environment can significantly alter the radiative properties of microwave emitters, and it explores several methods for informed environmental design.
The research begins by investigating the characteristic modes of a system consisting of three cyclically positioned, vertically coupled steel rod scatterers. This study shows how alterations, such as changing the separation distance and introducing asymmetry, can significantly impact the evolution of these characteristic modes. The introduction of a driving source further examines how coupling perturbations affect these modes, illustrating the complexity introduced by minor changes in seemingly simple systems and highlighting the advantages of using computational algorithms to analyse larger systems.
Building on this foundation, the thesis investigates the design and validation of complex, tailored multi-scatterer systems with desired radiative behaviours, in collaboration with James Capers from the University of Exeter. An iterative design algorithm is tested and validated through the fabrication, simulation, and experimental characterization of systems designed to achieve specified radiation patterns. This study also explores the limitations of the iterative design algorithm and suggests improvements for future research.
The thesis then focuses on experimentally realizing and validating an iterative Purcell-based design method in the microwave domain. This study details the design, computational modelling, fabrication, experimental characterization, and analysis of a bespoke dielectric resonator antenna. Inspired by the Purcell effect, a custom dielectric surround is designed to enhance emission at frequencies below the natural resonance of the driving source by coupling into tailored cavity modes. The experimental results demonstrate multiple near-perfect efficiency modes at significantly lower frequencies than the driving source resonance.
The findings underscore the critical role of environmental design in optimizing microwave radiation, offering new pathways for the development of advanced antenna systems and other electromagnetic applications. This research contributes valuable methodologies and insights for future studies in electromagnetic wave manipulation and radiative behaviour control, and it provides ideas for further advancing this work. | en_GB |
