Controlling the Most Significant Grating Lobes in Two-Dimensional Beam-Steering Systems with Phase-Gradient Metasurfaces

Singh, K; Afzal, MU; Kovaleva, M; Esselle, KP

Controlling the Most Significant Grating Lobes in Two-Dimensional Beam-Steering Systems with Phase-Gradient Metasurfaces

Singh, K Afzal, MU Kovaleva, M Esselle, KP

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Publisher:: IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
Publication Type:: Journal Article
Citation:: IEEE Transactions on Antennas and Propagation, 2020, 68, (3), pp. 1389-1401
Issue Date:: 2020-03-01

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Field	Value	Language
dc.contributor.author	Singh, K
dc.contributor.author	Afzal, MU
dc.contributor.author	Kovaleva, M
dc.contributor.author	Esselle, KP
dc.date.accessioned	2020-11-15T06:54:56Z
dc.date.available	2020-11-15T06:54:56Z
dc.date.issued	2020-03-01
dc.identifier.citation	IEEE Transactions on Antennas and Propagation, 2020, 68, (3), pp. 1389-1401
dc.identifier.issn	0018-926X
dc.identifier.issn	1558-2221
dc.identifier.uri	http://hdl.handle.net/10453/144024
dc.description.abstract	© 2019 IEEE. High-directivity antenna systems that provide 2-D beam steering by rotating a pair of phase-gradient metasurfaces (PGMs) in the near field of a fixed-beam antenna, hereafter referred to as near-field meta-steering systems, are efficient, planar, simple, short, require less power to operate, and do not require antenna tilting. However, when steering the beam, such systems generate undesirable dominant grating lobes, which substantially limit their applications. Optimizing a pair of these metasurfaces to minimize the grating lobes using standard methods is nearly impossible due to their large electrical size and thousands of small features leading to high computational costs. This article addresses this challenge as follows. First, it presents a method to efficiently reduce the strength of 'offending' grating lobes by optimizing a supercell using Floquet analysis and multi-objective particle swarm optimization. Second, it investigates the effects of the transmission phase gradient of PGMs on radiation-pattern quality. It is shown that the number of dominant unwanted lobes in a 2-D beam-steering antenna system and their levels can be reduced substantially by increasing the transmission phase gradient of the two PGMs. This knowledge is then extended to 2-D beam-steering systems, where we demonstrate how to substantially reduce all grating lobes to a level below-20 dB for all beam directions, without applying any amplitude tapering to the aperture field. When steering the beam of two meta-steering systems with peak directivities of 30.5 and 31.4 dBi, within a conical volume with an apex angle of 96°, the variation in directivity is 2.4 and 3.2 dB, respectively. We also demonstrate that beam-steering systems with steeper gradient PGMs can steer the beam in a wider range of directions, require less mechanical rotation of metasurfaces to obtain a given scan range, and their beam steering is faster. The gap between the two metasurfaces in a near-field meta-steering system can be reduced to one-eighth of a wavelength with no significant effect on pattern quality.
dc.language	English
dc.publisher	IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
dc.relation	http://purl.org/au-research/grants/arc/DP190103352
dc.relation.ispartof	IEEE Transactions on Antennas and Propagation
dc.relation.isbasedon	10.1109/TAP.2019.2955244
dc.rights	© 2020 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.	en_US
dc.rights	info:eu-repo/semantics/embargoedAccess
dc.subject	0906 Electrical and Electronic Engineering, 1005 Communications Technologies
dc.subject.classification	Networking & Telecommunications
dc.title	Controlling the Most Significant Grating Lobes in Two-Dimensional Beam-Steering Systems with Phase-Gradient Metasurfaces
dc.type	Journal Article
utslib.citation.volume	68
utslib.for	0906 Electrical and Electronic Engineering
utslib.for	1005 Communications Technologies
pubs.organisational-group	/University of Technology Sydney/Faculty of Engineering and Information Technology
pubs.organisational-group	/University of Technology Sydney/Faculty of Engineering and Information Technology/School of Electrical and Data Engineering
pubs.organisational-group	/University of Technology Sydney
utslib.copyright.status	open_access	*
utslib.copyright.embargo	2022-03-01T00:00:00+1000Z
dc.date.updated	2020-11-15T06:54:46Z
pubs.issue	3
pubs.publication-status	Published
pubs.volume	68
utslib.citation.issue	3

Abstract:

© 2019 IEEE. High-directivity antenna systems that provide 2-D beam steering by rotating a pair of phase-gradient metasurfaces (PGMs) in the near field of a fixed-beam antenna, hereafter referred to as near-field meta-steering systems, are efficient, planar, simple, short, require less power to operate, and do not require antenna tilting. However, when steering the beam, such systems generate undesirable dominant grating lobes, which substantially limit their applications. Optimizing a pair of these metasurfaces to minimize the grating lobes using standard methods is nearly impossible due to their large electrical size and thousands of small features leading to high computational costs. This article addresses this challenge as follows. First, it presents a method to efficiently reduce the strength of 'offending' grating lobes by optimizing a supercell using Floquet analysis and multi-objective particle swarm optimization. Second, it investigates the effects of the transmission phase gradient of PGMs on radiation-pattern quality. It is shown that the number of dominant unwanted lobes in a 2-D beam-steering antenna system and their levels can be reduced substantially by increasing the transmission phase gradient of the two PGMs. This knowledge is then extended to 2-D beam-steering systems, where we demonstrate how to substantially reduce all grating lobes to a level below-20 dB for all beam directions, without applying any amplitude tapering to the aperture field. When steering the beam of two meta-steering systems with peak directivities of 30.5 and 31.4 dBi, within a conical volume with an apex angle of 96°, the variation in directivity is 2.4 and 3.2 dB, respectively. We also demonstrate that beam-steering systems with steeper gradient PGMs can steer the beam in a wider range of directions, require less mechanical rotation of metasurfaces to obtain a given scan range, and their beam steering is faster. The gap between the two metasurfaces in a near-field meta-steering system can be reduced to one-eighth of a wavelength with no significant effect on pattern quality.

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http://hdl.handle.net/10453/144024