Arbitrary Field Transformations Using Practical Cylindrical Metasurfaces

Metasurfaces, engineered surfaces composed of intricately designed unit cells, enable full control over electromagnetic waves. Despite the large body of literature focused on planar metasurfaces, their cylindrical counterparts were not as thoroughly investigated. As cylindrical metasurfaces become needed in various scenarios, a suitable theory and design principles for these structures come to be indispensable.

In literature, cylindrical metasurface design has been hampered by several difficulties. These issues are addressed one by one in this dissertation. First, a comprehensive multimodal wave matrix theory is derived to account for couplings that were not accurately captured by earlier methods. Secondly, a realistic coaxial feed, in contrast to idealized (fictitious) line current sources assumed in previous works, is characterized and integrated into metasurface design. Furthermore, earlier research efforts were restricted to single-input-single-output devices, while a more useful multiple-input-multiple-output device is demonstrated here. Finally, for the first time, spatial dispersion of the patterned metallic claddings used to realize metasurfaces is studied and incorporated into theoretical design. With these advances, rigorous analysis and efficient synthesis of cylindrical-metasurface-based devices are accomplished.

A practical azimuthal mode converter is presented and validated through simulation. This device converts a 0th azimuthal order coaxial excitation to a 1st azimuthal order output field, realizing orbital angular momentum generation. The reported design principles are widely applicable and can be employed to engineer various cylindrical-metasurface-based devices including beam-shaping shells, illusion devices and multi-functional metasurfaces.

Chair: Professor Anthony Grbic