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[IEEE 2018 Second International Conference on Electronics, Communication and Aerospace Technology (ICECA) - Coimbatore (2018.3.29-2018.3.31)] 2018 Second International Conference on Electronics, Communication and Aerospace Technology (ICECA) - Patterns Generation of Horizontal Dipole Array Embedded in Different Dielectric Slabs
摘要： A number of papers are available on the analysis of dipole arrays in free space. But the work on embedded dipoles in dielectric media is limited in open literature. The behavior and characteristics are completely changed when the dipoles are embedded in dielectric slab. In this paper horizontal dipole array embedded in different dielectric slabs and different slab thickness is considered. Based on which, and radiation patterns are generated. Such patterns are used in point-to-point communications, scan, and non-scan radar applications.
关键词： Antenna Arrays,Radiation Patterns,Embedded Antennas
更新于2025-09-23 15:22:29
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Improvement of 60 GHz transparent patch antenna array performance through specific double-sided micrometric mesh metal technology
摘要： This paper presents the performance of optically transparent 4 × 2 microstrip patch antenna arrays operating at 60 GHz and made from double-sided micrometric mesh metal layers. A high level of optical transparency (higher than 80%) over the entire visible light spectrum coupled with a sheet resistance lower than 0.5 Ω/sq of the mesh metal films are achieved. Microwave performance of the transparent antenna arrays has been performed from two different mesh ground plane patterns and compared with those of an opaque antenna array made of double-sided continuous metal films. A gain value equal to 13.6 dBi at 58.0 GHz has been recorded, against 15.6 dBi at 59.7 GHz for the opaque antenna array. The influence of the mesh structure and mesh parameters of the ground plane is investigated and discussed.
关键词： millimeter wave antenna,Micrometric metal mesh,optically transparent antenna.,microstrip antenna arrays
更新于2025-09-23 15:22:29
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Structural Coloration with Nonclose-Packed Array of Bidisperse Colloidal Particles
摘要： Colloidal crystals and glasses have their own photonic effects. Colloidal crystals show high reflectivity at narrowband, whereas colloidal glasses show low reflectivity at broadband. To compromise the opposite optical properties, a simple means is suggested to control the colloidal arrangement between crystal and glass by employing two different sizes of silica particles with repulsive interparticle potential. Monodisperse silica particles with repulsive potential spontaneously form crystalline structure at volume fraction far below 0.74. When two different sizes of silica particles coexist, the arrangement of silica particles is significantly influenced by two parameters: size contrast and mixing ratio. When the size contrast is small, a long-range order is partially conserved in the entire mixing ratio, resulting in a pronounced reflectance peak and brilliant structural color. When the size contrast is large, the long-range order is rapidly reduced along with mixing ratio. Nevertheless, a short-range order survives, which causes low reflectivity at a broad wavelength, developing faint structural colors. These findings offer an insight into controlling the colloidal arrangements and provide a simple way to tune the optical property of colloidal arrays for structural coloration.
关键词： colloidal arrays,colloids,mechanochromism,structural colors,repulsive potential
更新于2025-09-23 15:22:29
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Organic-inorganic hybrid perovskite – TiO2 nanorod arrays for efficient and stable photoelectrochemical hydrogen evolution from HI splitting
摘要： Solar-driven photoelectrochemical (PEC) hydrogen production offers a promising solution to simultaneously tackle the global energy crisis and the environmental pollution. Herein, we report a PEC cell of organic-inorganic hybrid perovskite (methylammonium lead iodide, MAPbI3)-TiO2 nanorod array (TNAs) for efficient and stable hydrogen evolution in aqueous hydrogen iodide (HI) solution. The built-in electric field created across the MAPbI3-TiO2 junction is able to efficiently separate the electron-hole pairs photogenerated in MAPbI3 with electrons quickly injected from MAPbI3 to TiO2, which are then transported along the one-dimensional TiO2 nanorod channels to the counter electrode to reduce proton to evolve hydrogen. The optimized MAPbI3-TNA PEC cell exhibits a high photocurrent density of 1.75 mA cm-2 at 0.14 V (vs. Ag/AgCl) under AM 1.5G illumination, which is able to stably produce molecular hydrogen at a rate of 33.3 mmol cm-2 h-1 for more than 8 h.
关键词： Perovskite,Nanorod arrays,Hydrogen evolution,Heterojunction,Photoelectrochemical
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE 13th Annual International Conference on Nano/Micro Engineered and Molecular Systems (NEMS) - Singapore, Singapore (2018.4.22-2018.4.26)] 2018 IEEE 13th Annual International Conference on Nano/Micro Engineered and Molecular Systems (NEMS) - Wafer-Scale Fabrication of V-Shaped Silicon Nano-Slit Arrays
摘要： This paper presents a strategy of fabricating v-shaped nano-slit arrays in silicon substrates at wafer scale, by using a three-step wet anisotropic etching method with the combination of a color-feed mechanism. Through careful mask design, nano-slits with various aspect ratios and sizes were obtained at wafer scale. The minimum feature size of the obtained nano-slits was 5 nm, which holds great potential in bio-molecule analysis such as DNA and protein detection and analysis.
关键词： uniformity,v-shaped nano-slit arrays,wet anisotropic etching,feature size
更新于2025-09-23 15:22:29
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CoPi/Co(OH)2 Modified Ta3N5 as New Photocatalyst for Photoelectrochemical Cathodic Protection of 304 Stainless Steel
摘要： In this work, CoPi and Co(OH)2 nanoparticles were deposited on the surface of Ta3N5 nanorod-arrays to yield a novel broad-spectrum response photocatalytic material for 304 stainless steel photocatalytic cathodic protection. The Ta3N5 nanorod-arrays were prepared by vapor-phase hydrothermal (VPH) and nitriding processes and characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV-Vis spectroscopy, respectively, to obtain morphologies, crystal structures, surface compositions, and light response range. In order to analyze the performance improvement mechanism of CoPi/Co(OH)2 on Ta3N5 nanorod-arrays, the electrochemical behavior of modi?ed and unmodi?ed Ta3N5 was obtained by measuring the open circuit potential and photocurrent in 3.5 wt% NaCl solution. The results revealed that the modi?ed Ta3N5 material better protects 304 stainless steel at protection potentials reaching ?0.45 V.
关键词： CoPi/Co(OH)2 modi?cation,cathodic protection,Ta3N5 nanorod-arrays,photocatalysis
更新于2025-09-23 15:22:29
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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) - A Technique to Suppress Mutual Coupling in Densely Packed Antenna Arrays Using Metamaterial Supersubstrate
摘要： A simple and practical technique for reducing the mutual coupling between neighbouring antennas is presented for application in densely packed antenna arrays. This is achieved by locating between the radiation elements a smaller patch with metamaterial decoupling structure (MTM-DS). In this case the radiating elements are circular patches and the MTM-DS is constructed from a hexagonal slit resonator. The consequence of implementing the MTM-DS patch is significant reduction in mutual coupling between adjacent radiating patches by 60%, improvement in impedance match by 200% and substantial increase in the antenna’s fractional bandwidth by 369%. Since the ground plane is unaltered the front-to-back ratio is unaffected too. The proposed technique is easily realizable and can be used effectively in beam scanning applications.
关键词： phased antenna arrays,metamaterial,Mutual coupling,microstrip antennas,beam scanning
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE Asian Solid-State Circuits Conference (A-SSCC) - Tainan, Taiwan (2018.11.5-2018.11.7)] 2018 IEEE Asian Solid-State Circuits Conference (A-SSCC) - A Sub-Picosecond Hybrid DLL for Large-Scale Phased Array Synchronization
摘要： A large-scale timing synchronization scheme for scalable phased arrays is presented. This approach utilizes a DLL co-designed with a subsequent 2.5GHz PLL. The DLL employs a low noise, fine/coarse delay tuning to reduce the in-band rms jitter to 323fs, an order of magnitude improvement over previous works at similar frequencies. The DLL was fabricated in a 65nm bulk CMOS process and was characterized from 27MHz to 270MHz. It consumes up to 3.3mW from a 1V power supply and has a small footprint of 0.036mm2.
关键词： phase noise,tracking loops,CMOS integrated circuits,radio frequency,phase locked loops,phased-arrays,delay-lines
更新于2025-09-23 15:22:29
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Angle-of-Arrival Measurement System Using Double RF Modulation Technique
摘要： A new technique for determining the angle of arrival (AoA) of an RF signal is presented. It is based on a cascaded modulator structure, where continuous wave light from an optical source is modulated by an incoming RF signal twice. The AoA of an RF signal can be determined by the system output RF signal power. The proposed structure is capable for measuring the AoA of both narrow and broadband RF signals. This overcomes the limitation in all previously reported photonics-based AoA measurement systems, which are applicable to either a single-frequency RF signal or a broadband RF signal. It also does not involve electrical components and high extinction ratio modulators, which are required in reported structures. Experimental results are presented that show an AoA measurement range of 0° to over 65° with errors of less than 1.9° for a microwave signal at 2.65 and 12.62 GHz. Results also show that the system is capable to measure the AoA of a pseudorandom binary sequence signal at a microwave frequency.
关键词： notch filters,Direction-of-arrival estimation,phased arrays,microwave photonics
更新于2025-09-23 15:22:29
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SYNTHESIS OF SPARSE OR THINNED LINEAR AND PLANAR ARRAYS GENERATING RECONFIGURABLE MULTIPLE REAL PATTERNS BY ITERATIVE LINEAR PROGRAMMING
摘要： It is shown in this paper that the problem of reducing the number of elements for multiple-pattern arrays can be solved by a sequence of reweighted (cid:2)1 optimizations under multiple linear constraints. To do so, conjugate symmetric excitations are assumed so that the upper and lower bounds for each pattern can be formulated as linear inequality constraints. In addition, we introduce an auxiliary variable for each element to define the common upper bound of both the real and imaginary parts of multiple excitations for different patterns, so that only linear inequality constraints are required. The objective function minimizes the reweighted (cid:2)1-norm of these auxiliary variables for all elements. Thus, the proposed method can be efficiently implemented by the iterative linear programming. For multiple desired patterns, the proposed method can select the common elements with multiple set of optimized amplitudes and phases, consequently reducing the number of elements. The radiation characteristics for each pattern, such as the mainlobe shape, response ripple, sidelobe level and nulling region, can be accurately controlled. Several synthesis examples for linear array, rectangular/triangular-grid and randomly spaced planar arrays are presented to validate the effectiveness of the proposed method in the reduction of the number of elements.
关键词： thinned arrays,planar arrays,reconfigurable arrays,Sparse arrays,iterative linear programming,linear arrays,multiple patterns
更新于2025-09-23 15:21:21