| dc.description.abstract | Recent developments in engineered electromagnetic materials, also known as metamaterials paved the way for new design approaches of unique and incomprehensible electromagnetic devices and structures using electromagnetic properties which are usually not available in nature. By taking advantage of Maxwell’s equation’s “form-invariance” under coordinate transformations, lately, a coordinate transformation-based approach was introduced to manipulate electromagnetic waves at will, which resulted in a non-homogeneous, anisotropic transformation media dictated by the coordinate transformation. This design approach is known as “transformation electromagnetics/optics (TE/TO)” and has steered many unconventional and seemingly-impossible unique electromagnetic devices such as, the electromagnetic invisibility cloak.
The concepts of TE/TO can be extended to a region containing electromagnetic sources, which is known as source transformations. This research focused on the understanding of the theoretical and mathematical foundation of the “transformation electromagnetics/optics” and based on the understanding of the TE/TO concepts, a phased array antenna with new elements where antenna performance is a function of structural and mechanical constraints is proposed using source transformations, where each antenna element is “pinwheel” shaped antenna element transformed from a dipole element in free-space using appropriate coordinate transformations. The transformed materials are derived and through numerical simulations the radiation properties of the proposed array are demonstrated. It is anticipated that the proposed complex-geometry array will have great potential for future applications in structurally integrated and conformal arrays for wireless communications, radars, and sensing.
Additionally, the TE/TO technique is employed to design a TO-based beam-steerer which enables beam-scanning with a single antenna element and an antenna array without using phase control circuits. The proposed beam-steerer is a TE/TO-based non-homogeneous, anisotropic material shell theoretically computed using coordinate transformations. Through full-wave simulations the beam-scanning performances of the TO-based beam-rotator was demonstrated and validated. Since the practical metamaterial implementation involves losses, numerical simulations are performed incorporating losses to the derived material parameters. While currently, numerical verifications are provided, in practice, these TO-approaches will require actively tunable material parameters. Significant advancements have been made by the material scientists to design tunable materials using different approaches, which could enable the implementation of the TO-based approach practically. | en_US |
