Advanced multi-band and ultrawideband antenna arrays

He, Yi

Advanced multi-band and ultrawideband antenna arrays

He, Yi

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Publication Type:: Thesis
Issue Date:: 2025

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Field	Value	Language
dc.contributor.author	He, Yi
dc.date.accessioned	2025-11-04T04:23:47Z
dc.date.available	2025-11-04T04:23:47Z
dc.date.issued	2025
dc.identifier.uri	http://hdl.handle.net/10453/190612
dc.description	University of Technology Sydney. Faculty of Engineering and Information Technology.	en_US.UTF-8
dc.description.abstract	The exponential growth of information exchange necessitates communication systems to cover broader frequency coverage for higher data capacity, deliver ultra-high-speed connections, and ensure uninterrupted, reliable service. To address these challenges, antenna arrays in wireless communication systems must be advanced to support broad frequency coverage while maintaining stable radiation performance. This thesis systematically explores key innovations in multi-band/ultrawideband (UWB) antenna arrays, presenting three major works. In Work 1, a smaller antenna operating in the high band (HB) within 1.36–2.72 GHz is embedded within the cavity of a larger antenna working in the low band (LB) within 0.8–0.96 GHz, employing an "embedded scheme" to achieve a compact size and multi-band operation. Innovative techniques make the LB antenna electromagnetically transparent at the HB, effectively suppressing cross-band interference. Consequently, both antennas operate independently while sharing a single compact aperture. In Work 2, a new compact buffering scheme is proposed, incorporating a specialized "buffering layer" between the LB and HB antennas. The buffering layer reduced the height of the larger LB antenna from 0.20λL to 0.087λL (λL is the wavelength at the lowest LB frequency) without compromising its performance. It also enhances the bandwidth of the HB antenna from 45.5% to 60.2%. The unwanted interference between the two-band antennas remains minimal, as the buffering layer traps energy within itself, preventing it from entering the port of the other antenna when one is excited. This design supports two broad frequency bands of 0.69-0.96 GHz in the LB and 1.47-2.7 GHz in the HB, with an impressively low profile of 0.087λL. In contrast to the previous works aimed at minimizing coupling between antennas, Work 3 leverages mutual coupling to enable UWB operation, resulting in a frequency-reconfigurable tightly coupled dipole array (FR-TCDA). This work addresses critical challenges faced by other TCDAs: significant efficiency reduction when attempting to achieve over a decade of bandwidth and wide-angle beam scanning. A combined bandwidth of 15.8:1 (0.37–5.85 GHz) is achieved through two frequency-reconfigurable states, delivering high radiation efficiency exceeding 95% and wide beam-scan angles of up to 70°. Together, these contributions deliver compact, interference-resilient antenna arrays with broad multi-band/UWB coverage, extended beam scanning, and high radiation efficiency, advancing the vision of ubiquitous 6G networks to bridge the digital divide and bolster global communication infrastructure.	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/10453/190612/1/thesis.pdf
dc.rights	info:eu-repo/semantics/openAccess
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	© 2025 Yi He
dc.rights	au.edu.uts.lib/cph
dc.title	Advanced multi-band and ultrawideband antenna arrays	en_US.UTF-8
dc.type	Thesis
utslib.copyright.status	open_access	*

Abstract:

The exponential growth of information exchange necessitates communication systems to cover broader frequency coverage for higher data capacity, deliver ultra-high-speed connections, and ensure uninterrupted, reliable service. To address these challenges, antenna arrays in wireless communication systems must be advanced to support broad frequency coverage while maintaining stable radiation performance. This thesis systematically explores key innovations in multi-band/ultrawideband (UWB) antenna arrays, presenting three major works. In Work 1, a smaller antenna operating in the high band (HB) within 1.36–2.72 GHz is embedded within the cavity of a larger antenna working in the low band (LB) within 0.8–0.96 GHz, employing an "embedded scheme" to achieve a compact size and multi-band operation. Innovative techniques make the LB antenna electromagnetically transparent at the HB, effectively suppressing cross-band interference. Consequently, both antennas operate independently while sharing a single compact aperture. In Work 2, a new compact buffering scheme is proposed, incorporating a specialized "buffering layer" between the LB and HB antennas. The buffering layer reduced the height of the larger LB antenna from 0.20λL to 0.087λL (λL is the wavelength at the lowest LB frequency) without compromising its performance. It also enhances the bandwidth of the HB antenna from 45.5% to 60.2%. The unwanted interference between the two-band antennas remains minimal, as the buffering layer traps energy within itself, preventing it from entering the port of the other antenna when one is excited. This design supports two broad frequency bands of 0.69-0.96 GHz in the LB and 1.47-2.7 GHz in the HB, with an impressively low profile of 0.087λL. In contrast to the previous works aimed at minimizing coupling between antennas, Work 3 leverages mutual coupling to enable UWB operation, resulting in a frequency-reconfigurable tightly coupled dipole array (FR-TCDA). This work addresses critical challenges faced by other TCDAs: significant efficiency reduction when attempting to achieve over a decade of bandwidth and wide-angle beam scanning. A combined bandwidth of 15.8:1 (0.37–5.85 GHz) is achieved through two frequency-reconfigurable states, delivering high radiation efficiency exceeding 95% and wide beam-scan angles of up to 70°. Together, these contributions deliver compact, interference-resilient antenna arrays with broad multi-band/UWB coverage, extended beam scanning, and high radiation efficiency, advancing the vision of ubiquitous 6G networks to bridge the digital divide and bolster global communication infrastructure.

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