Eliminating Reflections in Waveguide Bends Using a Metagrating-Inspired Semianalytical Methodology

Biniashvili, Liran; Epstein, Ariel

doi:10.1109/tap.2021.3111524

Cited by 11 publications

(13 citation statements)

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“…However, just to give the readers a flavor of the broad scope of research areas that have employed this concept, here we list a few of the main applications that have been introduced in the past few years. Metagratings have been employed for lensing [52], [65], [85]- [87], holograms [88], [89], generation of vortex beams [90], [91], sensors [92], [93], high-Q resonators [94], ultra-narrowband absorbers [95], [96], power splitters [97]- [99], spectrum splitters [100], optical computing [101], [102], engineering reactive near field profiles [103], waveguiding for mode conversion and elimination of reflections at the bends [104], [105], light emitting devices [106], metrology [107], photovoltaics [108], retroreflectors [109], space-to-surface wave converting surfaces [110], and waterborne acoustics [79].…”

Section: Metagratings For Various Applicationsmentioning

confidence: 99%

Metagratings for Efficient Wavefront Manipulation

Ra’di

Alù

2022

IEEE Photonics J.

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Recently, it was revealed that conventional gradient metasurfaces are fundamentally limited on their overall efficiency to reroute the impinging waves towards arbitrary directions in reflection and transmission. Their efficiency is particularly limited for extreme wavefront transformations. In addition, due to the fastly varying impedance profiles that these surfaces require, they usually need high-resolution fabrication processes, limiting their applicability and overall bandwidth of operation. To address these issues, the concept of metagrating was recently introduced, enabling engineered surfaces capable of manipulating light with unitary efficiency even in the limit of extreme wavefront manipulation. Metagratings are periodic or locally periodic arrays operated in the few-diffraction order regime. Their unit cell contains carefully designed scatterers that, in contrast with conventional metasurfaces, do not need to support a continuous gradient of surface impedance, and consequently are far simpler to fabricate and can afford broader bandwidths because of the larger footprint of the constituent elements. Tailoring the coupling towards the few available diffraction channels, metagratings enable wavefront transformations with high efficiency. In this paper, we review the physical mechanisms behind the functionality of metagratings and provide an overview and outlook of the recent progress in this field of science and technology.

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Section: Metagratings For Various Applicationsmentioning

confidence: 99%

Metagratings for Efficient Wavefront Manipulation

Ra’di

Alù

2022

IEEE Photonics J.

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“…For 90∘ bends, there are later papers in which finite-element methods are used [12,13]. For some other geometries, see [14–16].…”

Section: Introductionmentioning

confidence: 99%

Going round the bend: reflection and transmission of long waves by waveguide corners and labyrinths

Martin

2023

Proc. R. Soc. A.

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Long-wave asymptotic approximations are developed for two-dimensional acoustic waves along rigid ducts. The waves are scattered by obstacles, constrictions, bulges and/or bends. Matched asymptotic expansions are used, requiring the calculation of blockage coefficients, which are defined in terms of the solution of related potential-flow problems. The emphasis is on estimating reflection and transmission coefficients, correct to first order in the ratio of the waveguide width to the wavelength. Detailed results are given for sharp bends of arbitrary angle, including right-angled bends and hairpin bends. Applications to multiple scattering by labyrinthine structures are also made.

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“…Indeed, in recent years, extensive research on MGs revealed their efficiency in implementing beam-manipulation functionalities [20], [22]- [29]. In particular, at microwave frequencies, semianalytical methodologies directly yielding fabricationready design specifications have been devised, subsequently used to demonstrate (theoretically and experimentally) printedcircuit-board (PCB) MGs for perfect anomalous reflection [28], [30], [31], refraction [26], waveguide mode manipula-tions [32], [33], and arbitrary diffraction engineering [34]- [38]. Since MGs clearly excel in suppression spurious Floquet-Bloch (FB) modes, and funneling all the incoming power to specified directions in space, it would only be natural to try and harness this innovative concept to develop an efficient spatial filter for eliminating grating lobes in sparse antenna arrays [39].…”

Section: Introductionmentioning

confidence: 99%

Metagrating-Assisted High-Directivity Sparse Antenna Arrays For Scanning Applications

Kerzhner¹,

Epstein²

2022

Preprint

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We present an analytical scheme for designing metagrating-enhanced sparse antenna arrays. Unlike previous work, the proposed method does not involve time-consuming cost function optimizations, complex structural manipulations on the active array or demanding computational capabilities. Instead, it merely requires the integration of a passive metagrating (MG) superstrate, a planar periodic arrangement of subwavelength capacitively-loaded wires (meta-atoms), synthesized conveniently via a semianalytical procedure to guarantee suppression of grating lobes in the sparse configuration. Correspondingly, we extend previous formulations to enable excitation of the MG by the active array elements, deriving analytical relations connecting the passive and active element distribution and electrical properties with the scattered fields, eventually allowing resolution of the detailed device configuration leading to optimal directivity. Importantly, considering typical active array applications, the semianalytical synthesis scheme is further developed to take full advantage of the various degrees of freedom in the system, harnessing them to support scanning in a wide range of extreme angles while maintaining a single directive beam. The resultant methodology, verified in simulations to work well also for large finite arrays, offers an original path for mitigating grating lobes in sparse arrays with scanning capabilities, yielding a complete printed-circuit-board compatible design without relying on fullwave optimization.

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Eliminating Reflections in Waveguide Bends Using a Metagrating-Inspired Semianalytical Methodology

Cited by 11 publications

References 50 publications

Metagratings for Efficient Wavefront Manipulation

Metagratings for Efficient Wavefront Manipulation

Going round the bend: reflection and transmission of long waves by waveguide corners and labyrinths

Metagrating-Assisted High-Directivity Sparse Antenna Arrays For Scanning Applications

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