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[IEEE 2018 IEEE Asia-Pacific Conference on Antennas and Propagation (APCAP) - Auckland (2018.8.5-2018.8.8)] 2018 IEEE Asia-Pacific Conference on Antennas and Propagation (APCAP) - A Wide-Angle Pattern Reconfigurable Antenna Realized by Meta-surface
摘要： This paper presents a wide-angle pattern reconfigurable antenna which has good directivity. The main lobe direction of the pattern can be switched between (cid:537)=±45o when (cid:182)=90o in the whole working frequency band. In addition, the structure of the antenna can be divided into three layers. The bottom layer is a feed line. The middle layer is the ground with slots. And the top is a novel meta-surface (MS). Reconfiguration is designed to achieve by controlling the state of PIN diode switches on the MS. This antenna is low profile and small volume. And the working frequency is from 4.95GHz to 5.05GHz.
关键词： pattern reconfigurable antenna,Wide-angle,MS
更新于2025-09-19 17:15:36
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[IEEE 2018 IEEE International Symposium on Antennas and Propagation & USNC/URSI National Radio Science Meeting - Boston, MA, USA (2018.7.8-2018.7.13)] 2018 IEEE International Symposium on Antennas and Propagation & USNC/URSI National Radio Science Meeting - A Circularly Polarized Triple-Feed Multi-Beam Array Antenna Using Planar Magic- Ts
摘要： A circularly polarized triple-feed multi-beam array antenna employing two types of planar magic-Ts is proposed. The proposed array antenna, where each of the antenna elements are circularly polarized antennas provides three different radiation patterns in the x-z and y-z planes. The performance of the proposed antenna is experimentally evaluated. The 10-dB impedance bandwidth of the antenna is better than 3.1% and 3-dB axial ratio bandwidth is 0.81%. All these features make the proposed antenna very suitable for direction-of-arrival estimation antennas, beam steering antennas and wide-angle rectennas.
关键词： magic-T,wide-angle rectenna,direction-of-arrival estimation antenna,triple-feed,beam steering antenna
更新于2025-09-19 17:15:36
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Spoof plasmonic metasurfaces with catenary dispersion for two-dimensional wide-angle focusing and imaging
摘要： Despite tremendous efforts have been devoted to investigating the analogy between the surface plasmon polariton and its spoof counterparts, it remains elusive that a single thin spoof plasmonic metalens realize wide-angle focusing and wide field-of-view (FOV) imaging. Here, we propose a spoof plasmonic metasurface that can impart arbitrary phase with high transmittance, which is comprised of two-dimensional (2D) gradient spoof-insulator-spoof waveguides. With the developed catenary field and dispersion theory, their intrinsic physics are theoretically analyzed. As a proof of concept, a spoof plasmonic metalens with a thickness of 0.15λ has been elaborately designed and experimentally demonstrated for wide-angle (~170°) focusing and wide FOV (~40°) imaging. To the best of our knowledge, it is the first experimental demonstration of wide FOV imaging of a 2D object with single thin and planar metalens in the microwave regime. The proposed method offers a promising solution to compact cameras, integrated imaging, and detection systems.
关键词： catenary dispersion,microwave regime,spoof plasmonic metasurfaces,wide-angle focusing,wide FOV imaging
更新于2025-09-19 17:13:59
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Organic Solar Cells Based on Cellulose Nanopaper from Agroforestry Residues with Efficiency over 16% and Effectively Wide Angle Light Capturing
摘要： Cellulose nanopaper (CNP) was successfully demonstrated for the enhanced efficiency and effectively wide-angle light capturing of organic solar cells (OSCs). The highest power-conversion efficiency (PCE) is up to 16.17%, which is among the excellent results natural materials for OSCs. The effectively wide-angle harvesting is demonstrated in the range from -45 to 45 degrees. Importantly, when the incident angle is 45o, the JSC with CNP is 21.18 mA/cm2, while the corresponding JSC without CNP is only 15.11 mA/cm2, an increase of ~40% is observed. The present PCEs of are found to be enhanced from 9.12% to 12.78%.
关键词： power-conversion efficiency,wide-angle harvesting,organic solar cells,light capturing,Cellulose nanopaper
更新于2025-09-19 17:13:59
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Rooma??Temperature Partial Conversion of ?±a??FAPbI <sub/>3</sub> Perovskite Phase via PbI <sub/>2</sub> Solvation Enables Higha??Performance Solar Cells
摘要： The two-step conversion process consisting of metal halide deposition followed by conversion to hybrid perovskite has been successfully applied toward producing high-quality solar cells of the archetypal MAPbI3 hybrid perovskite, but the conversion of other halide perovskites, such as the lower bandgap FAPbI3, is more challenging and tends to be hampered by the formation of hexagonal nonperovskite polymorph of FAPbI3, requiring Cs addition and/or extensive thermal annealing. Here, an efficient room-temperature conversion route of PbI2 into the α-FAPbI3 perovskite phase without the use of cesium is demonstrated. Using in situ grazing incidence wide-angle X-ray scattering (GIWAXS) and quartz crystal microbalance with dissipation (QCM-D), the conversion behaviors of the PbI2 precursor from its different states are compared. α-FAPbI3 forms spontaneously and efficiently at room temperature from P2 (ordered solvated polymorphs with DMF) without hexagonal phase formation and leads to complete conversion after thermal annealing. The average power conversion efficiency (PCE) of the fabricated solar cells is greatly improved from 16.0(±0.32)% (conversion from annealed PbI2) to 17.23(±0.28)% (from solvated PbI2) with a champion device PCE > 18% due to reduction of carrier recombination rate. This work provides new design rules toward the room-temperature phase transformation and processing of hybrid perovskite films based on FA+ cation without the need for Cs+ or mixed halide formulation.
关键词： FAPbI3,two-step conversion,high performance,hybrid perovskite solar cells,quartz-crystal microbalance,in situ grazing incidence wide angle x-ray scattering
更新于2025-09-16 10:30:52
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Markedly different molecular formation in DPP-based small-molecule solar cells probed by grazing-incidence wide-angle X-ray scattering
摘要： This study comprehensively explores the nanostructural properties of two diketopyrrolo[3,4-c]pyrrole-1,4-dione (DPP)-based small molecules with different alkyl side groups and their blends with the fullerene derivative PC71BM, using grazing-incidence wide-angle X-ray scattering synchrotron techniques. Preferentially relative face-on orientation within the larger and more ordered stacking phase of SM1 with its shorter side group (ethylhexyl) was observed in the majority of both pristine and blend thin films, whereas SM2 crystals showed strictly perpendicular orientation. These contrasting crystalline characteristics led to significant differences in the results, from which crystalline structure–performance property correlations are proposed. Thus, the results not only demonstrate important scientific insights into the relationship between molecular structure and crystalline formation but also provide molecular design directions that will facilitate further improvement to the morphology and performance of DPP-based small-molecule solar cells.
关键词： small-molecule donors,diketopyrrolopyrrole,grazing-incidence wide-angle X-ray scattering,molecular packing structure,small-molecule solar cells
更新于2025-09-11 14:15:04
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Highly Efficient Indoor Organic Solar Cells by Voltage Losses Minimization through Fine-tuning of Polymer Structures
摘要： Herein we report a detailed study on the optoelectronic properties, photovoltaic performance, structural conformation, morphology variation, charge carrier mobility and recombination dynamics in bulk heterojunction (BHJ) solar cells comprising of a series of donor-acceptor (D-A) conjugated polymers as electron donors based on benzodithiophene (BDT) and 5,8-bis(5-bromothiophen-2-yl)-6,7-difluoro-2,3-bis(3-(octyloxy)phenyl)quinoxaline as a function of the BDT’s thienyl substitution (alkyl (WF3), alkylthio (WF3S) and fluoro (WF3F)). It is manifested the synergistic positive effects of the fluorine substituents on the minimization of the bimolecular recombination losses, the reduction of the series resistances (RS), the increment of the shunt resistances (RSh), the suppression of the trap-assisted recombination losses, the balanced charge transport, the finer nanoscale morphology and the deeper highest occupied molecular orbital (EHOMO) versus the alkyl- and alkylthio- substituents. According to these findings, WF3F:[6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) based-organic photovoltaic (OPV) device is a scarce example that feature a high power conversion efficiency (PCE) of 17.34% under 500 lx indoor LED light with a high open-circuit voltage (VOC) of 0.69 V, due to the suppression of the voltage losses and a PCE of 9.44% at 1-sun (100 mW/cm2) conditions, simultaneously.
关键词： Series and Shunt resistances,Coherence length,Conjugated polymers,Wide-angle X-ray scattering,Organic photovoltaic devices,Recombination losses,Indoor lighting conditions
更新于2025-09-11 14:15:04
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Research on a Novel Kind of Dual Polarized Stacked Printed Antenna
摘要： This paper presents a dual polarized antenna with high isolation for a wide-angle scanning phased array radar. For the proposed antenna, the electronic and magnetic resources are realized through a printed monopole antenna and a slot ring antenna, respectively. A metal reflector ground was introduced to achieve the unidirectional pattern, and the ratio of front to back of the pattern was improved. The printed monopole and slot ring antenna are fed by the coaxial and electromagnetic couplings, respectively. The radiation fields emitted by the electronic current resource and magnetic current resource are approximately orthogonal to each other among large space ranges. The measured port isolation of the designed antenna is above 20 dB, and the wide beam performance can be observed. The feasibility of the proposed antenna scheme is verified.
关键词： dual polarized antenna,high isolation,printed monopole antenna,phased array radar,slot ring antenna,wide-angle scanning
更新于2025-09-11 14:15:04
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Joint Sparsity Constraint Interferometric ISAR Imaging for 3-D Geometry of Near-Field Targets with Sub-Apertures
摘要： This paper proposes a new interferometric near-field 3-D imaging approach based on multi-channel joint sparse reconstruction to solve the problems of conventional methods, i.e., the irrespective correlation of different channels in single-channel independent imaging which may lead to deviated positions of scattering points, and the low accuracy of imaging azimuth angle for real anisotropic targets. Firstly, two full-apertures are divided into several sub-apertures by the same standard; secondly, the joint sparse metric function is constructed based on scattering characteristics of the target in multi-channel status, and the improved Orthogonal Matching Pursuit (OMP) method is used for imaging solving, so as to obtain high-precision 3-D image of each sub-aperture; thirdly, comprehensive sub-aperture processing is performed using all sub-aperture 3-D images to obtain the final 3-D images; finally, validity of the proposed approach is verified by using simulation electromagnetic data and data measured in the anechoic chamber. Experimental results show that, compared with traditional interferometric ISAR imaging approaches, the algorithm proposed in this paper is able to provide a higher accuracy in scattering center reconstruction, and can effectively maintain relative phase information of channels.
关键词： interferometric inverse synthetic aperture radar,compressed sensing,joint sparse reconstruction,wide angle,near-field 3-D imaging
更新于2025-09-10 09:29:36
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[IEEE 2018 IEEE 23rd International Conference on Emerging Technologies and Factory Automation (ETFA) - Torino, Italy (2018.9.4-2018.9.7)] 2018 IEEE 23rd International Conference on Emerging Technologies and Factory Automation (ETFA) - Vision System with High Performance Wide Angle Fovea Lens
摘要： This paper designs and produces a single camera head, i.e., the camera view direction control device, for the high-performance Wide Angle Fovea (WAF) sensor. Since the input image by the WAF sensor has an explicit attention region inside its wide-angle field of view (FOV), the view direction control of the WAF sensor is strongly required to acquire visual data most efficiently from the environments. Further, this paper proposes an algorithm to detect self-motion of the WAF sensor using the optical flow calculated from two temporally-sequential images. We have implemented and experimented this algorithm. The experimental results have proved the proposed algorithm performs well to detect self-motion using only the peripheral FOV. This vision system enables to distinguish the self-motion from detecting moving objects in the still scene. The authors hope this WAF vision system will play a role of eyes and will help to control robots more intelligently in the very near future.
关键词： view direction control,self-motion detection,single camera head,wide angle fovea sensor,optical flow
更新于2025-09-10 09:29:36