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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) - Ka-band Metasurface Antenna for Data Downlink from LEO Satellites
摘要： This paper presents design, realization and measurements of a prototype of metasurface antenna radiating a sectoral beam with isoflux envelope. The prototype, developed for data-downlink applications from LEO satellites, is fed by a circular waveguide and can be associated to a turn table mechanism to provide the same Earth coverage as a conical isoflux beam, with the benefit of a higher gain.
关键词： metasurface antenna,antenna design,leaky wave antennas
更新于2025-09-23 15:23:52
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Anti-reflection high-index metasurfaces combining Mie and Fabry-Pérot resonances
摘要： Minimizing reflection losses is required for the efficient operation of a wide range of optical components. Anti-reflection coatings supporting Fabry-Pérot resonances are commonly used to solve this problem and can be applied on an industrial scale. Recent work has shown that reflections can also be reduced by placing an array of high-index nanostructures on a surface. In such coatings, anti-reflection is achieved by tailoring the scattering by optical Mie resonances. Here, we design and fabricate Si metasurfaces that combine both Fabry-Pérot and Mie resonances in a single metasurface to realize a multi-resonant broadband anti-reflection response. We optically characterize the metasurfaces demonstrating 4.1% AM1.5–averaged reflectance across the visible spectrum (425–900 nm). Our metasurface design strategy is generally applicable to different materials and frequency ranges, making our approach relevant for a broad variety of applications.
关键词： Mie resonators,Metasurface,Effective Medium,Anti-Reflection Coating (ARC),Fabry-Pérot resonances
更新于2025-09-23 15:23:52
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Enhancement of local electromagnetic fields by periodic optical resonators
摘要： The periodically profiled metasurfaces of silicon and of the same surfaces coated with a thin layer of silver are experimentally investigated to improve the signal-to-noise ratio in the observation of Raman light scattering from molecular compounds. The noise in this case is the unavoidable background molecular luminescence. Our experimental and computer simulation data demonstrate an anomalous optical response due to the excitation of metal-dielectric surface resonances. An enhanced Raman scattering signal is observed from 5,5'-dithiobis(2-nitrobenzoic) acid (DTNB) organic molecules deposited on the metasurface. The proposed metasurface provides a significant enhancement of the RS signal in comparison with the luminescence signal and is an efficient substrate for realising giant Raman scattering of light.
关键词： silicon,metasurface,dielectric resonators,nanostructures,plasmon resonance,giant Raman scattering of light
更新于2025-09-23 15:23:52
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Spin-Selective Transmission in Chiral Folded Metasurfaces
摘要： Controlling the spin angular momentum of light (or circular polarization state) plays a crucial role in the modern photonic applications such as optical communication, circular dichroism spectroscopy, and quantum information processing. However, the conventional approaches to manipulate the spin of light require naturally occurring chiral or birefringent materials of bulky sizes due to the weak light-matter interactions. Here we experimentally demonstrate an approach to implement spin-selective transmission in the infrared region based on chiral folded metasurfaces that are capable of transmitting one spin state of light while largely prohibiting the other. Due to the intrinsic chirality of the folded metasurface, a remarkable circular dichroism as large as 0.7 with the maximum transmittance exceeding 92% is experimentally demonstrated. The giant circular dichroism is interpreted within the framework of charge-current multipole expansion. Moreover, the intrinsic chirality can be readily controlled by manipulating the folding angle of the metasurface with respect to the cardinal plane. Benefiting from its strong chirality and spin-dependent transmission characteristics, the proposed folded metasurface may be applied to a range of novel photon-spin selective devices for optical communication technologies and bio-photonics.
关键词： sub-wavelength optics,Folded metasurface,intrinsic chirality,spin-selective transmission
更新于2025-09-23 15:23:52
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Simultaneous Control of the Spatial and Temporal Spectra of Light with Space-Time Varying Metasurfaces
摘要： This paper presents space-time varying (STV) metasurfaces for simultaneously controlling the spatial and temporal spectra of electromagnetic waves. These metasurfaces transform incident electromagnetic waves into specified reflected and transmitted waves, with arbitrary temporal and spatial frequencies. They are synthesized in terms of time-domain generalized sheet transition conditions (GSTCs). Moreover, they are characterized using an analytical method and the unstaggered finite-difference time-domain (FDTD) technique adapted to space-time metasurfaces. STV metasurfaces performing pulse shaping, time reversal and differentiation are demonstrated as examples.
关键词： space-time varying (STV) medium,Metasurface,generalized sheet transition conditions (GSTC)
更新于2025-09-23 15:22:29
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Lightweight Ultra-Wideband RCS Reduction Structure using Double-Layer Metasurfaces
摘要： In this paper, we propose the design of a lightweight RCS reduction structure using double-layer metasurfaces. The structure is composed of two layers of metasurfaces spaced by PMI foams. To extend the bandwidth, two unit structures are firstly designed to operating in two respective bands for circularly polarized (CP) waves, which are then combined to act as the unit structure of the double-layer metasurface. The metasurface is expected to operate in two continuous bands. Nevertheless, due to the couplings between the two unit structures, there is Fano resonance that prohibits merging of the two bands. To solve this problem, we tune the resonant frequency of the bottom unit structure to suppress the Fano resonance and obtain a merged band. The combined unit structure is employed as the element of chessboard configuration, which can reduce RCS by more than 10dB in an ultra-wideband (4.5-16.5GHz). We designed, fabricated and measured a lightweight prototype (the aerial density is 726g/m2). Both the simulation and experiment result verify the design. This work provides an effective method of extending the operation band of RCS reduction without sacrificing the efficiency.
关键词： metasurface,ultra-wideband,Fano resonance,RCS reduction
更新于2025-09-23 15:22:29
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Scattered EM-wave Shaping Using Combination of Cross Polarization Conversion and Reflection Phase Cancellation
摘要： The design of millimeter wave 1-bit coding engineered reflector for backscattered electromagnetic wave shaping by combining both cross-polarization conversion and reflection phase cancellation principles is presented in this article. The anisotropic unit cell of the presented engineered reflector can efficiently rotate the polarization of an incident EM wave to its orthogonal one at millimeter wave regime. Each unit cell has four inverted L-shape copper resonators on the top side of a PEC backed dielectric substrate. The proposed unit cell has three plasmon resonance frequencies at 87.3GHz, 90.1GHz and 91.8GHz with 100% cross-polarization conversion efficiency at these frequencies and more than 92.1% from about 86.7GHz to 91.9GHz. Moreover, if the proposed anisotropic unit cell (“0” element) along with its mirrored one (“1” element) are arranged in one engineered reflector, an 180o±25o reflection phase difference is valid between their reflection phases and engineered reflectors that can efficiently manipulate the reflected EM-wave and generates many kinds of scattering patterns such as two lobes, three lobes, four lobes or even a diffuse scattering pattern can be composed using only those two unit cells. Full wave simulation, fabrication and experimental characterization results are presented.
关键词： metasurface,diffuse reflection,reflectarray,reflective surface
更新于2025-09-23 15:22:29
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A shared aperture 1-bit metasurface for orbital angular momentum multiplexing
摘要： In this letter, a shared aperture 1-bit metasurface for orbital angular momentum (OAM) multiplexing is studied. A phased array antenna fed by the phase shift network is embedded on the reflective aperture of the 1-bit metasurface. The proposed device can work on reflectarray mode from 7.1GHz to 7.5GHz and phased array mode from 7GHz to 7.5GHz. Correspondingly, OAM vortex beam with topological charge l = -1 and l = 1 can be generated. The transmission coefficient between the two working modes is below -30dB and the envelop correlation coefficient (ECC) is quite close to 0, which reveals the excellent isolation and diversity performance. A prototype of the proposed device is fabricated and tested. The measured S parameters and radiation patterns agree well with the simulation results.
关键词： phased array,reflectarray,metasurface,Orbital angular momentum (OAM) multiplexing
更新于2025-09-23 15:22:29
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Autofocusing with out-of-band phase conjugation
摘要： Electromagnetic phase conjugation provides an appealing path towards communication and target localization in dynamic media such as the Earth’s atmosphere. However, realizing phase conjugation-based devices has proven difficult because of the inherent complexity of systems that employ receivers and transmitters working on the same band. In this letter we propose the concept of out-of-band phase conjugation in which the frequency of the phase conjugated wave is an integer multiple of the incident wave frequency. Remarkably, the out-of-band phase conjugated wave maintains the autofocusing property that makes phase conjugation so powerful and opens the door to imaging technology effective in random and dynamic media.
关键词： Phase Conjugation,Retrodirective Arrays,Metasurface,Active Metamaterial,Time Reversal
更新于2025-09-23 15:21:21
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[IEEE 2018 7th International Conference on Computer and Communication Engineering (ICCCE) - Kuala Lumpur, Malaysia (2018.9.19-2018.9.20)] 2018 7th International Conference on Computer and Communication Engineering (ICCCE) - CPW-Fed Patch Antenna with Reflecting Metasurface Covering for WLAN and WiMAX Applications
摘要： A coplanar waveguide (CPW)-fed multiband patch antenna with the integration reflecting metasurface covering has been designed and performance characteristics are critically analyzed. The proposed low profile antenna can offers the wireless communications services for WLAN and WiMAX applications. The rectangular shaped patch antenna consists of pair of C-, L- and splitted-T shape slotted radiator, and 2D reflective metasurface covering at the back of patch which is separated by dielectric layer of substrate. The details of the antenna design structure and performance criteria are discussed through numerical simulation using full-wave electromagnetic simulator. The simulation results shows that by employing the reflecting metasurface covering, the -10dB impedance bandwidth has considerably increased than the typical CPW-fed patch antenna: from 440 MHz to 570 MHz (29%), 390 MHz to 480 MHz (23%) and 900 MHz to 1060 MHz (18%) for three different operating bands centered at 2.5, 3.5 and 5.5 GHz respectively. The simulated result shows the antenna with RMC integration achieves peak gain of 6.56 dBi, 6.43 dBi and 6.97 dBi with average gain of 6.45 dBi, 6.27 dBi and 6.82 dBi at three operating bands respectively which are higher than the typical patch antenna.
关键词： patch antenna,low-profile,reflecting metasurface covering,CPW-fed,WiMAX/WLAN Applications,radiation pattern improvement
更新于2025-09-23 15:21:21