Near-Field Metallic Metasurfaces for High-Performance Antenna Systems
- Publication Type:
- Thesis
- Issue Date:
- 2022
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| Filename | Description | Size | |||
|---|---|---|---|---|---|
| 01front.pdf | contents and abstract | 182.56 kB | |||
| 02whole.pdf | thesis | 214.8 MB |
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The massive demand for data rates aggravated the situation when the Coronavirus Disease 2019 (COVID-19) pandemic forced everything online. To support data-hungry wireless devices and applications, high-speed data connectivity is indispensable. Cost-effective low-earth-orbit satellite links promise a dependable, robust, and viable solution for seamless high-speed internet connectivity, even where terrestrial technologies are ineffective. High-gain beam-steering antennas are the most crucial and costly radio-frequency (RF) technology for mobile satellite communications. Metasurface-driven antennas may offer an affordable alternative, but existing approaches often employ heavy or expensive dielectric-based metasurfaces. The weights and RF losses of dielectrics make them less attractive for practical applications. Also, they are not preferable in space due to environmental challenges (e.g., carbonization, high radiation, and cryogenic temperature). In high-power microwave systems, they can lead to dielectric breakdown. Metasurfaces built on all-metal architecture could be potential substitutes, but there is limited research, and many opportunities are yet to be explored.
The research efforts in this thesis focus on the innovative design strategy of metallic metasurfaces (MMs). The proposed approaches adopt new techniques to synthesize entirely dielectric-free, self-sustained, polarization-independent, and fabrication-friendly MMs, significantly reducing the weight and cost of low-loss dielectrics. The novel slots-in-sheets (SiS) architecture proposed in constructing MMs retains structural rigidity – a distinctive design feature from the state-of-the-art. Several antenna designs have been analyzed and tested experimentally to evaluate the efficacy of the proposed solutions. First, novel MMs are synthesized to correct the aperture near-field phase non-uniformity of shortened horns and resonant cavity antennas. The study also explains wideband gain-bandwidth improvement employing MMs thoroughly. Then, the potential research gaps are addressed by developing an entirely new dual-band phase-correcting MM and ultra-thin, single-layer dual-band metallic partially reflective surface for the first time. Secondly, the research tackles the design challenges of phase gradient MMs compatible with the near-field meta-steering (NFMS) system. First, a wideband NFMS system with measured scanning bandwidths of at least 700 MHz is demonstrated. Further research advances the field significantly by developing a novel dual-band NFMS system of its first kind operating in full-duplex simultaneously. A methodology has been devised to design compact dual-band cells with greater freedom in tuning parameters to attain complete 360o phase shifts with excellent transmission efficiency.
Overall, the proposed antennas radically depart from traditional dielectric-based metasurfaces and exhibit excellent performance, making them expedient for modern satellite communications. They are also contenders for many cutting-edge applications, including high-power systems and deep space exploration.
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