Electromagnetic Isolation Induced by Time-Varying Metasurfaces: Nonreciprocal Bragg Grating

Ramaccia, Davide; Sounas, Dimitrios L.; Marini, A.; Toscano, Alessandro; Bilotti, Filiberto

doi:10.1109/lawp.2020.2996275

Cited by 47 publications

(28 citation statements)

References 23 publications

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“…The light blue curve represents the results for any value of 0.05 p tT  that satisfies Eq. (19). In this case, the curve is monotonic, and there is no ambiguity on the DoA.…”

Section: B 1d Doa Estimation Using Different Time Delaysmentioning

confidence: 91%

Accurate Direction-of-Arrival Estimation Method based on Space-Time Modulated Metasurface

Li¹

2022

Preprint

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In this paper, we present a metasurface-based Direction of Arrival (DoA) estimation method that exploits the properties of space-time modulated reflecting metasurfaces to estimate in real-time the impinging angle of an illuminating monochromatic plane wave. The approach makes use of the amplitude unbalance of the received fields at broadside at the frequencies of the two first-order harmonics generated by the interaction between the incident plane wave and the modulated metasurface. Here, we first describe analytically how to generate the desired higher-order harmonics in the reflected spectrum and how to realize the breaking of the spatial symmetry of each order harmonic scattering pattern. Then, the one dimensional (1D) omnidirectional incident angle can be analytically computed using +1st and -1st order harmonics. The approach is also extended to 2D DoA estimation by using two orthogonally arranged 1D DoA modulation arrays. The accuracy of 1D DoA estimation is verified through full-wave numerical simulations. Compared to conventional DoA estimation methods, the proposed approach simplifies the computation and hardware complexity, ensuring at the same time estimation accuracy. The proposed method may have potential applications in wireless communications, target recognition, and identification.

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“…The light blue curve represents the results for any value of 0.05 p tT  that satisfies Eq. (19). In this case, the curve is monotonic, and there is no ambiguity on the DoA.…”

Section: B 1d Doa Estimation Using Different Time Delaysmentioning

confidence: 91%

Accurate Direction-of-Arrival Estimation Method based on Space-Time Modulated Metasurface

Li¹

2022

Preprint

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“…This concept has been employed in Doppler cloaks for restoring the invisibility of dynamic cloaked objects. [13][14][15][16][17] Further, the planar configuration of metasurfaces enables easy implementation at terahertz (THz) and visible spectra using standard photolithography. These extra-ordinary properties and capabilities exhibited by metasurfaces 18 have led to its application in a wide gamut of fields such as signal multiplexing, stealth technology, holographic imaging, planar optical devices, and polarization transformation devices.…”

Section: Overview Of Metasurfacesmentioning

confidence: 99%

Metasurfaces for Stealth Applications: A Comprehensive Review

Joy¹,

Dileep

Abhilash³

et al. 2021

J. Electron. Mater.

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Metasurfaces are ultrathin, two-dimensional structures composed of periodic or quasi-periodic arrays of sub-wavelength scatterers. They possess the unique ability to comprehensively control the phase, amplitude and polarization of incident electromagnetic waves with added advantages such as ease of fabrication and less space consumption. On account of these factors, they are progressively replacing their three-dimensional counterparts, i.e. metamaterials in a wide gamut of fields such as signal multiplexing, stealth technology, holographic imaging, planar optical devices, polarization transformation devices and so on. Further, metasurfaces offer a strong and promising platform for aerospace applications due to their diversified functionalities and reduced weight penalties. Moreover, it has been widely used for the realization of thin, broadband and polarization independent radar absorbing structures (RAS). In this regard, this paper presents a concise review on the recent advancements in the field of metasurfaces specifically for stealth applications. Special emphasis has been laid on diffusion and coding metasurfaces due to their attractive properties towards the realization of low observable platforms. Furthermore, various types of metasurfaces as well as the different techniques used for the optimization of metasurfaces are also described in detail.

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“…The localization and confinement of electromagnetic energy in a finite volume without dissipation has been extensively studied by the scientific community in the last years, by exploiting the anomalous interaction between light and artificial metastructures [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. In this framework, virtual absorption concept [20][21][22][23][24] represents one of the most appealing technique for storing and releasing electromagnetic energy, due to passive and simple structures that can support the desired energy accumulation.…”

Section: Introductionmentioning

confidence: 99%

Metasurface virtual absorbers: unveiling operative conditions through equivalent lumped circuit model

et al. 2021

Self Cite

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Virtual absorption concept has been recently introduced as a new phenomenon observed in electromagnetics and optics consisting of theoretically unlimited accumulation of energy within a finite volume of material without dissipation. The anomalous behaviour is achieved by engaging the complex zero scattering eigenmodes of the virtual absorbing system by illuminating it with a proper complex frequency ω = ω r + jω i , whose value is strictly determined by the system characteristics. In this paper, we investigate on the position of the zero-pole scattering pairs in the complex frequency plane as a function of the input impedance of the metasurface-based lossless virtual absorber. We analytically derive the conditions under which a properly modulated monochromatic plane wave can be virtually absorbed by the system and stored within its volume. The analysis is developed by modelling the propagation of a normally impinging plane wave through its equivalent transmission line model terminated in an arbitrary reactive load, which in turn models the input impedance of the metasurface-based system under consideration. The study allows to determine a priori whether the metasurface-based system can support the virtual absorption or not by evaluating the time-constant from its equivalent circuit.

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Electromagnetic Isolation Induced by Time-Varying Metasurfaces: Nonreciprocal Bragg Grating

Cited by 47 publications

References 23 publications

Accurate Direction-of-Arrival Estimation Method based on Space-Time Modulated Metasurface

Accurate Direction-of-Arrival Estimation Method based on Space-Time Modulated Metasurface

Metasurfaces for Stealth Applications: A Comprehensive Review

Metasurface virtual absorbers: unveiling operative conditions through equivalent lumped circuit model

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