- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Combining Frequency-Selective Scattering and Specular Reflection Through Phase-Dispersion Tailoring of a Metasurface
摘要： Re?ective metasurfaces (or meta-mirrors) composed of arti?cially engineered subwavelength structures provide an alternate paradigm for arbitrarily controlling wave re?ection with high e?ciency. We introduce the concept of frequency-selective coding of a meta-mirror to perform desired scattering properties in different frequency bands by tailoring the phase dispersion of the metasurface. As a particular example, broadband backward-scattering reduction and high-e?cient specular re?ection are combined by a single meta-mirror in a frequency-selective manner. Two meta-atoms with optimized metallic patterns are used as the binary coding elements to realize an out-of-phase function in two side-bands, while the in-phase function is in the center frequency window. Then, we experimentally demonstrate that polarization-insensitive di?usion-like scatterings can be achieved by the proposed meta-mirror with randomly distributed meta-atoms in two side-bands from 7.5 to 9.5 GHz and 11.6 to 15 GHz, while in the selected center frequency window around 10.7 GHz, a high-e?cient specular re?ection property is realized. The experimental results are in good agreement with the full-wave simulations. Compared with the conventional meta-surface designs for scattering reduction, the proposed concept exhibits a frequency-selective e?ect and hence can be used in many practical applications, for example, working as the ground plane of antennas to enable a high-e?cient in-band radiation with out-of-band low-backward scattering.
关键词： specular reflection,meta-mirrors,frequency-selective scattering,metasurfaces,phase dispersion tailoring
更新于2025-09-04 15:30:14
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[IEEE 2018 International Conference on Microwave and Millimeter Wave Technology (ICMMT) - Chengdu, China (2018.5.7-2018.5.11)] 2018 International Conference on Microwave and Millimeter Wave Technology (ICMMT) - Polarization-Dependent Full-Space Beam Steering with Orbital-Angular-Momentum Mode by Anisotropic Coding Metasurface
摘要： Coding metasurfaces have attracted much attention in recent years. Here, we propose a novel polarization-dependent full-space beam-steering anisotropic coding metasurface to radiate beams with orbital-angular-momentum (OAM) modes. When the polarizations of incident electromagnetic waves are orthogonal, the beams can be emitted to the upper and lower half spaces with different coding information, respectively. A scheme is presented to radiate multiple OAM modes with different deflecting angles to the corresponding spaces. This work has great potentials in multi-target communications and tracking radar systems.
关键词： coding metasurfaces,orbital-angular-momentum (OAM),multi-target communications,polarization-dependent,beam-steering,tracking radar systems
更新于2025-09-04 15:30:14
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Heat Resisting Metallic Meta-Skin for Simultaneous Microwave Broadband Scattering and Infrared Invisibility Based on Catenary Optical Field
摘要： Metallic skins are widely used in practical engineering owing to their inherent advantages in mechanical and physical characteristics. In this paper, a metasurface skin composed of subwavelength metallic gratings with space-variant orientations has been proposed to realize exotic electromagnetic properties in microwave and infrared regimes. Equivalent circuit theory and transfer matrix method have been adopted to quantitatively describe the optical fields and dispersion with high accuracy in a catenary form. Based on these analyses, broadband and wide-angle radar cross-section (RCS) reduction for microwave has been simulated and experimentally demonstrated. Additional characteristics such as high temperature resistance and low infrared thermal emission are also verified. It is believed that these results may provide a new platform to achieve multifunctional electromagnetic devices and are promising for many applications.
关键词： scattering,catenary optics,metasurface,thermal emission,all-metal metasurfaces
更新于2025-09-04 15:30:14
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[Institution of Engineering and Technology 12th European Conference on Antennas and Propagation (EuCAP 2018) - London, UK (9-13 April 2018)] 12th European Conference on Antennas and Propagation (EuCAP 2018) - Retrodirective Metasurface Operating Simultaneously at Multiple Incident Angles
摘要： Metasurfaces are the subject of intensive research in several applicative areas. The concept of anomalous re?ection has for instance been proposed to demonstrate retrodirectivity. Retrodirectivity can be very attractive feature particularly for radar applications at microwave and millimeter wave frequencies where the enhancement of the radar cross-section of poorly scaterring targets is desirable. In this paper, the design of a retrodirective metasurface operating at multiple incident angles is proposed. It is based on the principle of introducing several super-cells; each supercell being designed according to the generalized Snells law of re?ection thus retro-re?ecting an incoming wave at a speci?c desired angle with high ef?ciency. Angles of incidence ranging from 10? to 30? have been considered. Based on these designs, a novel retrodirective metasurface is proposed such that multiple incident angles are simultaneously addressed. To highlight the applicative potential of this metasurface for RCS enhancement, particularly at large incident angles, a comparison is presented between the RCS of this novel retrodirective metasurface and a conventional metallic corner dihedral. Although the RCS in the angular range -10? to 10? is lower compared with respect to the corner dihedral, a gain of up to 50 dB of monostatic RCS is obtained between -30? to -20? and 20? to 30?. First measurements results for the validation of simulation results for an incident plane wave at 30? are presented.
关键词： gradient-index metamaterial,retrodirectivity,metasurfaces,RCS enhancement
更新于2025-09-04 15:30:14
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[Institution of Engineering and Technology 12th European Conference on Antennas and Propagation (EuCAP 2018) - London, UK (9-13 April 2018)] 12th European Conference on Antennas and Propagation (EuCAP 2018) - Concept of an Asymmetric Metasurface Absorber
摘要： In this talk we show how to break the angular symmetry of electromagnetic response of thin absorbers. Based on our recent results on multichannel metasurfaces, we propose a new concept of asymmetric absorbers in which the absorption coefficient for waves impinging from a given oblique angle is extraordinarily different from that for waves incident from the oppositely tilted direction. The proposed asymmetric structure realizes controllable reflectance (from 0 to 0.99) for waves incident from one direction, exhibiting total absorption when the sign of the incidence angle is reversed. We provide a theoretical analysis for the asymmetric absorber as well as a numerical verification.
关键词： surface impedances,asymmetric,Floquet harmonics,absorbers,multichannel metasurfaces
更新于2025-09-04 15:30:14
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Extreme Asymmetry in Metasurfaces via Evanescent Fields Engineering: Angular-Asymmetric Absorption
摘要： On the quest towards full control over wave propagation, the development of compact devices that allow asymmetric response is a challenge. In this Letter, we introduce a new paradigm for the engineering of asymmetry in planar structures, revealing and exploiting unilateral excitation of evanescent waves. We test the idea with the design and experimental characterization of a metasurface for angular-asymmetric absorption. The results show that the contrast ratio of absorption (the asymmetry level) can be arbitrarily engineered from zero to infinity for waves coming from two oppositely tilted angles. We demonstrate that the revealed asymmetry effects cannot be realized using conventional diffraction gratings, reflectarrays, and phase-gradient metasurfaces. This Letter opens up promising possibilities for wave manipulation via evanescent waves engineering with applications in one-side detection and sensing, angle-encoded steganography, flat nonlinear devices, and shaping the scattering patterns of various objects.
关键词： evanescent waves,metasurfaces,wave manipulation,asymmetric absorption
更新于2025-09-04 15:30:14
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Resonant Beam Steering and Carpet Cloaking Using an Acoustic Transformational Metascreen
摘要： We invoke the Huygens principle to derive dispersion characteristics of acoustic transformational metasurfaces that can deflect parallel wavefronts in a desired direction. We also propose a dual-Lorentz resonator whose aperture fields can be tuned by geometrical changes to implement a particular phase with unity reflection coefficient. The proposed metascreen is designed by our arranging slightly detuned Lorentz cavities that generate the necessary interference to compensate for the incident wavefronts. Since a complete 0–2π range of the reflection phase is achieved, the metascreen can steer a beam across the full horizon. Moreover, since the proposed dual resonator has subwavelength dimensions, the metascreen is capable of high-resolution imaging, which is an essential trait in cloaking and deceptive acoustics. Successful demonstration of acoustic beam steering and carpet cloaking is done for a wavelength of 790 mm with the help of full-wave simulations.
关键词： carpet cloaking,acoustic transformational metasurfaces,Huygens principle,beam steering,dual-Lorentz resonator
更新于2025-09-04 15:30:14
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[Institution of Engineering and Technology 12th European Conference on Antennas and Propagation (EuCAP 2018) - London, UK (9-13 April 2018)] 12th European Conference on Antennas and Propagation (EuCAP 2018) - Metallic Metasurface Antennas for Space
摘要： In metasurface (MTS) antennas, a surface-wave (SW) is gradually radiated by modulating an equivalent reactance tensor in the aperture plane. Such modulation results in the (-1) indexed Floquet mode entering the visible region, thus becoming a leaky-wave (LW) mode with curvilinear phase-contour. This paper explores the use of a class of metallic MTS in the synthesis of the reactance tensor required to obtain the objective radiation patterns. The absence of dielectric is useful to survive harsh environments in space exploration. The proposed element consists of a metallic cylinder with elliptical cross-section, placed on a ground plane and arranged in a square lattice with sub-wavelength unit-cell side. We have applied this structure in the design of a right-handed circularly polarized antenna, with a broadside pencil beam in the Ka band. The obtained performance has been veri?ed by full-wave simulations. A prototype has been manufactured and measurements will be available at the time of the conference.
关键词： surface waves,leaky waves,metasurfaces,circular polarization,millimeter waves,Ka band
更新于2025-09-04 15:30:14