Advanced Conformal Transmitarrays for 5G and Beyond Wireless Communications

Song, Lizhao

Advanced Conformal Transmitarrays for 5G and Beyond Wireless Communications

Song, Lizhao

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Publication Type:: Thesis
Issue Date:: 2021

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Field	Value	Language
dc.contributor.author	Song, Lizhao
dc.date.accessioned	2022-04-12T04:52:21Z
dc.date.available	2022-04-12T04:52:21Z
dc.date.issued	2021
dc.identifier.uri	http://hdl.handle.net/10453/156118
dc.description	University of Technology Sydney. Faculty of Engineering and Information Technology.	en_US.UTF-8
dc.description.abstract	Transmitarray antennas (TAs) have received considerable attention as they can serve long-distance communications for space and terrestrial wireless systems. For many wireless communication platforms, such as aircrafts and unmanned aerial vehicles (UAV), conformal TAs, which can be flush mounted onto the shaped platforms, are highly demanded in order to meet the aerodynamic requirements. In this dissertation, a few innovative techniques have been developed for conformal TAs. Firstly, a thin frequency selective surfaces (FSS) element is developed with a thickness of 0.508 mm (0.04λ₀ at 25 GHz). It is then applied to a curved TA conformal to a cylindrical surface. The prototype radiates a fixed boresight beam with a peak measured gain of 19.6 dBi and an aperture efficiency of 25.1%. Secondly, a mechanical beam-scanning conformal TA is proposed. Its size is about 2.5 times of the fixed-beam one, steering its beam to seven different radiation angles, i.e., ±15°, ±10°, ±5°, and 0°. The measured prototype shows a stable gain of 18.7 dBi at all beam angles. Thirdly, to improve the aperture efficiency of conformal TAs further, Huygens metasurface theory is employed to design a dual-layer TA element. The element is composed of two metal layers printed on a single substrate with a 0.5-mm thickness (0.017λ₀ at 10 GHz). The oblique incidence effects are also considered in the process of element synthesis. Finally, a cylindrically conformal TA is developed, which achieves a measured gain of 20.6 dBi with a 47% aperture efficiency. Fourthly, by combining connected arrays and true-time-delay lines, a novel technique is introduced to obtain ultrawideband (UWB) TAs. The elements consist of a horizontally connected slot bowtie and vertical meander slot-lines. The TAs have been designed in both planar and conformal configurations. Stable boresight radiation patterns from 6 GHz to 17 GHz are obtained for both antennas. Compared to conformal TAs using multi-layer FSS elements, the proposed one has an ultra-wide bandwidth of 96% in terms of stable radiation patterns. Fifthly, a conformal TA, with an elliptical cylindrical contour at a millimetre-wave (mm-wave) band, is presented for wide-angle multibeam radiations. A systematic design procedure is developed. The prototype provides eleven beams with a beam coverage of ±43°. The measured peak boresight gain is 27 dBi at 70.5 GHz with a less than 2.7-dB scanning loss.	en_US.UTF-8
dc.format	Thesis (PhD)
dc.language.iso	en_US	en_US.UTF-8
dc.relation	https://opus.lib.uts.edu.au/bitstream/10453/156118/2/02whole.pdf
dc.rights	The author owns the copyright in this thesis including all reproduction and reuse rights for the work. The work may not be altered without the permission of the copyright owner. Attribution is essential when quoting or paraphrasing from this thesis.
dc.rights	au.edu.uts.lib/ppc
dc.rights	info:eu-repo/semantics/openAccess
dc.title	Advanced Conformal Transmitarrays for 5G and Beyond Wireless Communications	en_US.UTF-8
dc.type	Thesis
utslib.copyright.status	open_access	*

Abstract:

Transmitarray antennas (TAs) have received considerable attention as they can serve long-distance communications for space and terrestrial wireless systems. For many wireless communication platforms, such as aircrafts and unmanned aerial vehicles (UAV), conformal TAs, which can be flush mounted onto the shaped platforms, are highly demanded in order to meet the aerodynamic requirements. In this dissertation, a few innovative techniques have been developed for conformal TAs. Firstly, a thin frequency selective surfaces (FSS) element is developed with a thickness of 0.508 mm (0.04λ₀ at 25 GHz). It is then applied to a curved TA conformal to a cylindrical surface. The prototype radiates a fixed boresight beam with a peak measured gain of 19.6 dBi and an aperture efficiency of 25.1%. Secondly, a mechanical beam-scanning conformal TA is proposed. Its size is about 2.5 times of the fixed-beam one, steering its beam to seven different radiation angles, i.e., ±15°, ±10°, ±5°, and 0°. The measured prototype shows a stable gain of 18.7 dBi at all beam angles. Thirdly, to improve the aperture efficiency of conformal TAs further, Huygens metasurface theory is employed to design a dual-layer TA element. The element is composed of two metal layers printed on a single substrate with a 0.5-mm thickness (0.017λ₀ at 10 GHz). The oblique incidence effects are also considered in the process of element synthesis. Finally, a cylindrically conformal TA is developed, which achieves a measured gain of 20.6 dBi with a 47% aperture efficiency. Fourthly, by combining connected arrays and true-time-delay lines, a novel technique is introduced to obtain ultrawideband (UWB) TAs. The elements consist of a horizontally connected slot bowtie and vertical meander slot-lines. The TAs have been designed in both planar and conformal configurations. Stable boresight radiation patterns from 6 GHz to 17 GHz are obtained for both antennas. Compared to conformal TAs using multi-layer FSS elements, the proposed one has an ultra-wide bandwidth of 96% in terms of stable radiation patterns. Fifthly, a conformal TA, with an elliptical cylindrical contour at a millimetre-wave (mm-wave) band, is presented for wide-angle multibeam radiations. A systematic design procedure is developed. The prototype provides eleven beams with a beam coverage of ±43°. The measured peak boresight gain is 27 dBi at 70.5 GHz with a less than 2.7-dB scanning loss.

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