Optimization of Metamaterial-enabled Antennas
Open Access
- Author:
- Binion, John
- Graduate Program:
- Electrical Engineering
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- June 14, 2021
- Committee Members:
- Michael Lanagan, Outside Unit & Field Member
Douglas Werner, Chair & Dissertation Advisor
Julio Urbina, Major Field Member
Victor Pasko, Major Field Member
Kultegin Aydin, Program Head/Chair - Keywords:
- Metamaterials
Metasurface
Antenna
Global Optimization - Abstract:
- Metamaterial-enabled antennas have been shown to achieve unprecedented performance enhancements in terms of gain, efficiency, and size reduction, when compared to traditional antenna designs. Here, the unique properties of metamaterials are harnessed to improve two antenna systems: the short backfire antenna (SBFA), and the electronically scanned array (ESA). Though the conventional SBFA is compact and achieves relatively high gain, its versatility is limited by a narrow bandwidth, circular geometry, and moderate aperture efficiency. A new, hexagonal SBFA with metasurface-lined walls has been developed to address these shortcomings. The metasurfaces are anisotropic and dispersive, enabling high aperture efficiency and low cross-polarization at two frequency bands, greatly extending the functionality of this antenna, and increasing its suitability for a wide variety of applications. A circular, dual-band A-SBFA is then optimized to perform at 100% aperture efficiency over a wide range of aperture sizes. The A-SBFA is further augmented with tunable-metasurfaces that enable beam steering in both planes. In the case of a conventional ESA, lossy and costly feed networks are typically required, and the element spacing must not exceed λ/2 to avoid the creation of grating lobes. Additionally, for arrays with high-gain antenna elements, significant scan-loss can occur when steering to wider angles as the steered beam follows the envelope of the embedded element pattern. A metamaterial lens (metalens) is optimized to transform the embedded element pattern of a sparse array into a flat-top pattern, enabling two-dimensional beam steering with greatly increased gain, suppressed grating lobes, and reduced scan loss, allowing for cheaper, more efficient, and simpler ESA designs. These results demonstrate the ability of metamaterials to transform practical antenna systems.