The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Jieqiu Zhang - One of the best experts on this subject based on the ideXlab platform.
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two dimensional coding Phase Gradient metasurface for rcs reduction
Journal of Physics D, 2018Co-Authors: Maochang Feng, Hongya Chen, Jiafu Wang, Jieqiu Zhang, Qiqi Zheng, Yajuan Han, Sui SaiAbstract:A two-dimensional (2D) coding Phase Gradient metasurface (CPGM) is proposed for radar cross section (RCS) reduction in this work. The 2D Phase Gradient super cell is employed to serve as the coding element. The primary pattern of the coding element will be modulated by the designed 2D Phase Gradient. Thus, a more flexible method of scattering manipulation will be achieved by both the 2D Phase Gradient and coding sequences. The specific scattering patterns of the 2D CPGM under the modulation of Phase Gradient and coding sequence were analyzed. A controllable backward diffusion scattering coding Phase Gradient metasurface was realized based on Pancharatnam–Berry Phase by modulating both the Phase Gradient and coding sequence. Both simulated and measured results demonstrate its excellent performance on RCS reduction.
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Frequency Scanning Radiation by Decoupling Spoof Surface Plasmon Polaritons via Phase Gradient Metasurface
IEEE Transactions on Antennas and Propagation, 2018Co-Authors: Jiafu Wang, Yongfeng Li, Shaobo Qu, Jieqiu Zhang, Hongya ChenAbstract:On the basis of generalized Snell's law of reflection, we propose to achieve frequency scanning radiation by decoupling spoof surface plasmon polaritons (SSPPs) from a corrugated metallic strip (CMS). Phase Gradient metasurface (PGM) is utilized to modulate the dispersion behavior of the CMS. Since the Phase Gradient of the PGM is contrary to the wave vector of SSPPs, the dispersion curve of SSPPs can be translated into the fast wave zone, leading to frequency scanning radiation. As an example, we demonstrate a frequency scanning antenna operating at 8.8-10.7 GHz. A prototype was designed, fabricated, and measured. The measured results show that the prototype can realize continuous beam scanning from 4.8° to 37.2°, with realized gain varying from 8 to 13.1 dB. Owing to surface confinement of SSPPs, the proposed method can be readily extended to the design of conformal frequency scanning antennas on curved faces.
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wideband wide angle coding Phase Gradient metasurfaces based on pancharatnam berry Phase
Scientific Reports, 2017Co-Authors: Qiqi Zheng, Jiafu Wang, Jieqiu Zhang, Yajuan Han, Yongqiang Pang, Sai Sui, Yang Shen, Hongya ChenAbstract:A new concept of the coding Phase Gradient metasurface (CPGM) is proposed, which is constructed using the Phase Gradient metasurface as the coding elements. Different from the previous coding metasurface (CM), both the coding sequences and Gradient Phases in the coding elements are designed to manipulate the electromagnetic (EM) wave for the CPGMs, and thus the manipulation will be more flexible. As an example, wide-band, wide-angle CPGMs with zero and non-zero Phase Gradient based on Pancharatnam-Berry (PB) Phase are achieved using the co-polarization reflection unit cells under circularly polarized (CP) wave incidence. Both theoretically calculated and numerically simulated scattering patterns of the designed CPGMs demonstrate the expected manipulations. Additionally, two kinds of random CPGMs with different Phase Gradients are designed for radar cross section (RCS) reduction, and the measured RCS reveals a good accordance with the simulation.
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in plane feed antennas based on Phase Gradient metasurface
IEEE Transactions on Antennas and Propagation, 2016Co-Authors: Ya Fan, Jiafu Wang, Jieqiu Zhang, Dayi Feng, Mingde FengAbstract:We propose the design of in-plane feed antennas (IPFA) based on Phase Gradient metasurface (PGM). The in-plane feed is realized using PGM with large in-plane Phase Gradient, which can couple normally incident waves efficiently into surface waves along the surface. This is different from conventional reflector antennas and reflectarray antennas, where the focus lies above the reflector. As an example, an IPFA is demonstrated, which is composed of a superthin PGM and a waveguide feeding structure. Due to the large Phase Gradient of the PGM toward the feeding waveguide, incident waves can be coupled as surface waves into the waveguide; whereas transmitted waves can be radiated out along the normal of the PGM. Both the simulated and experimental results verify the high gain and high efficiency of the IPFA with in a broad band in 3.0–3.2 GHz.
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k dispersion engineering of spoof surface plasmon polaritons for beam steering
Optics Express, 2016Co-Authors: Jieqiu Zhang, Jiafu Wang, Mingde Feng, Jing WangAbstract:In this paper, we propose to achieve beam steering by k-dispersion engineering of spoof surface plasmon polaritons (spoof SPP) at microwave frequencies. The planar plasmonic metamaterials (PPMs) are employed to couple and guide spoof SPP. High-efficiency transmission based on spoof SPP coupling is realized via matching the wave-vectors of the spoof SPP and the space wave. The transmission Phase can be modulated by k-dispersion engineering of the spoof SPP with great freedom. Due to the independent Phase shift produced by the spoof SPP on the PPMs, the Phase Gradient achieved by using the PPMs as the sub-unit cells can be altered by changing the repetition period of the sub-unit cells. Two Phase Gradient materials (PGMs) are achieved by using nine different PPMs as the sub-unit cells with the repetition period q = 4mm and 4.5mm. Both the simulated and measured results demonstrated the excellent performances of the PGMs on high efficiency, wideband, tunable beam steering.
Jiafu Wang - One of the best experts on this subject based on the ideXlab platform.
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two dimensional coding Phase Gradient metasurface for rcs reduction
Journal of Physics D, 2018Co-Authors: Maochang Feng, Hongya Chen, Jiafu Wang, Jieqiu Zhang, Qiqi Zheng, Yajuan Han, Sui SaiAbstract:A two-dimensional (2D) coding Phase Gradient metasurface (CPGM) is proposed for radar cross section (RCS) reduction in this work. The 2D Phase Gradient super cell is employed to serve as the coding element. The primary pattern of the coding element will be modulated by the designed 2D Phase Gradient. Thus, a more flexible method of scattering manipulation will be achieved by both the 2D Phase Gradient and coding sequences. The specific scattering patterns of the 2D CPGM under the modulation of Phase Gradient and coding sequence were analyzed. A controllable backward diffusion scattering coding Phase Gradient metasurface was realized based on Pancharatnam–Berry Phase by modulating both the Phase Gradient and coding sequence. Both simulated and measured results demonstrate its excellent performance on RCS reduction.
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wideband frequency scanning spoof surface plasmon polariton planar antenna based on transmissive Phase Gradient metasurface
IEEE Antennas and Wireless Propagation Letters, 2018Co-Authors: Hongya Chen, Yongfeng Li, Jiafu Wang, Shaobo QuAbstract:A novel design of spoof surface plasmon polariton (SSPP) planar antenna is proposed based on the wave vector modulation of transmissive Phase Gradient metasurface (TPGM). The antenna consists of TPGM placed a certain distance above SSPP guided wave structure, exhibiting the directional radiation property according to the generalized Snell's law. As an example, an SSPP planar antenna fed by rectangular waveguide is designed by using a wideband polarization rotating TPGM. Simulated and experimental results, agreeing well with each other, show that the planar antenna can achieve wideband frequency scanning from backward to forward. Compared to existing planar antennas, our SSPP planar antenna has advantages of wideband frequency scanning characteristic, higher efficiency, and higher degree of freedom for designing frequency scanning antenna, which would possibly open an avenue in designing conformal antennas and other new types of antennas.
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Frequency Scanning Radiation by Decoupling Spoof Surface Plasmon Polaritons via Phase Gradient Metasurface
IEEE Transactions on Antennas and Propagation, 2018Co-Authors: Jiafu Wang, Yongfeng Li, Shaobo Qu, Jieqiu Zhang, Hongya ChenAbstract:On the basis of generalized Snell's law of reflection, we propose to achieve frequency scanning radiation by decoupling spoof surface plasmon polaritons (SSPPs) from a corrugated metallic strip (CMS). Phase Gradient metasurface (PGM) is utilized to modulate the dispersion behavior of the CMS. Since the Phase Gradient of the PGM is contrary to the wave vector of SSPPs, the dispersion curve of SSPPs can be translated into the fast wave zone, leading to frequency scanning radiation. As an example, we demonstrate a frequency scanning antenna operating at 8.8-10.7 GHz. A prototype was designed, fabricated, and measured. The measured results show that the prototype can realize continuous beam scanning from 4.8° to 37.2°, with realized gain varying from 8 to 13.1 dB. Owing to surface confinement of SSPPs, the proposed method can be readily extended to the design of conformal frequency scanning antennas on curved faces.
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wideband wide angle coding Phase Gradient metasurfaces based on pancharatnam berry Phase
Scientific Reports, 2017Co-Authors: Qiqi Zheng, Jiafu Wang, Jieqiu Zhang, Yajuan Han, Yongqiang Pang, Sai Sui, Yang Shen, Hongya ChenAbstract:A new concept of the coding Phase Gradient metasurface (CPGM) is proposed, which is constructed using the Phase Gradient metasurface as the coding elements. Different from the previous coding metasurface (CM), both the coding sequences and Gradient Phases in the coding elements are designed to manipulate the electromagnetic (EM) wave for the CPGMs, and thus the manipulation will be more flexible. As an example, wide-band, wide-angle CPGMs with zero and non-zero Phase Gradient based on Pancharatnam-Berry (PB) Phase are achieved using the co-polarization reflection unit cells under circularly polarized (CP) wave incidence. Both theoretically calculated and numerically simulated scattering patterns of the designed CPGMs demonstrate the expected manipulations. Additionally, two kinds of random CPGMs with different Phase Gradients are designed for radar cross section (RCS) reduction, and the measured RCS reveals a good accordance with the simulation.
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in plane feed antennas based on Phase Gradient metasurface
IEEE Transactions on Antennas and Propagation, 2016Co-Authors: Ya Fan, Jiafu Wang, Jieqiu Zhang, Dayi Feng, Mingde FengAbstract:We propose the design of in-plane feed antennas (IPFA) based on Phase Gradient metasurface (PGM). The in-plane feed is realized using PGM with large in-plane Phase Gradient, which can couple normally incident waves efficiently into surface waves along the surface. This is different from conventional reflector antennas and reflectarray antennas, where the focus lies above the reflector. As an example, an IPFA is demonstrated, which is composed of a superthin PGM and a waveguide feeding structure. Due to the large Phase Gradient of the PGM toward the feeding waveguide, incident waves can be coupled as surface waves into the waveguide; whereas transmitted waves can be radiated out along the normal of the PGM. Both the simulated and experimental results verify the high gain and high efficiency of the IPFA with in a broad band in 3.0–3.2 GHz.
Hongya Chen - One of the best experts on this subject based on the ideXlab platform.
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two dimensional coding Phase Gradient metasurface for rcs reduction
Journal of Physics D, 2018Co-Authors: Maochang Feng, Hongya Chen, Jiafu Wang, Jieqiu Zhang, Qiqi Zheng, Yajuan Han, Sui SaiAbstract:A two-dimensional (2D) coding Phase Gradient metasurface (CPGM) is proposed for radar cross section (RCS) reduction in this work. The 2D Phase Gradient super cell is employed to serve as the coding element. The primary pattern of the coding element will be modulated by the designed 2D Phase Gradient. Thus, a more flexible method of scattering manipulation will be achieved by both the 2D Phase Gradient and coding sequences. The specific scattering patterns of the 2D CPGM under the modulation of Phase Gradient and coding sequence were analyzed. A controllable backward diffusion scattering coding Phase Gradient metasurface was realized based on Pancharatnam–Berry Phase by modulating both the Phase Gradient and coding sequence. Both simulated and measured results demonstrate its excellent performance on RCS reduction.
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wideband frequency scanning spoof surface plasmon polariton planar antenna based on transmissive Phase Gradient metasurface
IEEE Antennas and Wireless Propagation Letters, 2018Co-Authors: Hongya Chen, Yongfeng Li, Jiafu Wang, Shaobo QuAbstract:A novel design of spoof surface plasmon polariton (SSPP) planar antenna is proposed based on the wave vector modulation of transmissive Phase Gradient metasurface (TPGM). The antenna consists of TPGM placed a certain distance above SSPP guided wave structure, exhibiting the directional radiation property according to the generalized Snell's law. As an example, an SSPP planar antenna fed by rectangular waveguide is designed by using a wideband polarization rotating TPGM. Simulated and experimental results, agreeing well with each other, show that the planar antenna can achieve wideband frequency scanning from backward to forward. Compared to existing planar antennas, our SSPP planar antenna has advantages of wideband frequency scanning characteristic, higher efficiency, and higher degree of freedom for designing frequency scanning antenna, which would possibly open an avenue in designing conformal antennas and other new types of antennas.
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Frequency Scanning Radiation by Decoupling Spoof Surface Plasmon Polaritons via Phase Gradient Metasurface
IEEE Transactions on Antennas and Propagation, 2018Co-Authors: Jiafu Wang, Yongfeng Li, Shaobo Qu, Jieqiu Zhang, Hongya ChenAbstract:On the basis of generalized Snell's law of reflection, we propose to achieve frequency scanning radiation by decoupling spoof surface plasmon polaritons (SSPPs) from a corrugated metallic strip (CMS). Phase Gradient metasurface (PGM) is utilized to modulate the dispersion behavior of the CMS. Since the Phase Gradient of the PGM is contrary to the wave vector of SSPPs, the dispersion curve of SSPPs can be translated into the fast wave zone, leading to frequency scanning radiation. As an example, we demonstrate a frequency scanning antenna operating at 8.8-10.7 GHz. A prototype was designed, fabricated, and measured. The measured results show that the prototype can realize continuous beam scanning from 4.8° to 37.2°, with realized gain varying from 8 to 13.1 dB. Owing to surface confinement of SSPPs, the proposed method can be readily extended to the design of conformal frequency scanning antennas on curved faces.
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wideband wide angle coding Phase Gradient metasurfaces based on pancharatnam berry Phase
Scientific Reports, 2017Co-Authors: Qiqi Zheng, Jiafu Wang, Jieqiu Zhang, Yajuan Han, Yongqiang Pang, Sai Sui, Yang Shen, Hongya ChenAbstract:A new concept of the coding Phase Gradient metasurface (CPGM) is proposed, which is constructed using the Phase Gradient metasurface as the coding elements. Different from the previous coding metasurface (CM), both the coding sequences and Gradient Phases in the coding elements are designed to manipulate the electromagnetic (EM) wave for the CPGMs, and thus the manipulation will be more flexible. As an example, wide-band, wide-angle CPGMs with zero and non-zero Phase Gradient based on Pancharatnam-Berry (PB) Phase are achieved using the co-polarization reflection unit cells under circularly polarized (CP) wave incidence. Both theoretically calculated and numerically simulated scattering patterns of the designed CPGMs demonstrate the expected manipulations. Additionally, two kinds of random CPGMs with different Phase Gradients are designed for radar cross section (RCS) reduction, and the measured RCS reveals a good accordance with the simulation.
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achieving wideband polarization independent anomalous reflection for linearly polarized waves with dispersionless Phase Gradient metasurfaces
Journal of Physics D, 2014Co-Authors: Jieqiu Zhang, Hongya Chen, Jiafu Wang, Lin Zheng, Anxue ZhangAbstract:In this letter, we proposed to achieve wideband polarization-independent anomalous reflection for linearly polarized (LP) waves based on the Phase Gradient metasurface (PGM) with a dispersionless Phase Gradient. A polarization-keeping metasurface reflector for circularly polarized (CP) waves was firstly presented. Based on the reflector, a reflective PGM was designed to realize dispersionless but adverse Phase Gradients for left- and right-handed circularly polarized (LCP and RCP, respectively) waves. Under normal incidence, high-efficiency anomalous reflection occurs for both LCP and RCP waves with opposite-signed reflection angles. Under the LP wave incidence, the reflected waves are separated into two beams due to the decomposition of LP waves into LCP and RCP waves. The anomalous reflection of LP waves is independent of the polarization angle. Both the experimental and simulated results are consistent with theoretical predictions, which convincingly verifies the wideband polarization-independent anomalous reflection of LP waves.
Peter W Carr - One of the best experts on this subject based on the ideXlab platform.
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peak capacity optimization of peptide separations in reversed Phase Gradient elution chromatography fixed column format
Analytical Chemistry, 2006Co-Authors: Xiaoli Wang, Dwight R Stoll, And Adam P Schellinger, Peter W CarrAbstract:The optimization of peak capacity in Gradient elution RPLC is essential for the separation of multicomponent samples such as those encountered in proteomic research. In this work, we study the effect of Gradient time (tG), flow rate (F), temperature (T), and final eluent strength (phi(final)) on the peak capacity of separations of peptides that are representative of the range in peptides found in a tryptic digest. We find that there are very strong interactions between the individual variables (e.g., flow rate and Gradient time) which make the optimization quite complicated. On a given column, one should first set the Gradient time to the longest tolerable and then set the temperature to the highest achievable with the instrument. Next, the flow rate should be optimized using a reasonable but arbitrary value of phi(final). Last, the final eluent strength should be adjusted so that the last solute elutes as close as possible to the Gradient time. We also develop an easily implemented, highly efficient, and effective Monte Carlo search strategy to simultaneously optimize all the variables. We find that Gradient steepness is an important parameter that influences peak capacity and an optimum range of Gradient steepness exists in which the peak capacity is maximized.
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peak capacity optimization of peptide separations in reversed Phase Gradient elution chromatography fixed column format
Analytical Chemistry, 2006Co-Authors: Xiaoli Wang, Dwight R Stoll, And Adam P Schellinger, Peter W CarrAbstract:The optimization of peak capacity in Gradient elution RPLC is essential for the separation of multicomponent samples such as those encountered in proteomic research. In this work, we study the effect of Gradient time (tG), flow rate (F), temperature (T), and final eluent strength (φfinal) on the peak capacity of separations of peptides that are representative of the range in peptides found in a tryptic digest. We find that there are very strong interactions between the individual variables (e.g., flow rate and Gradient time) which make the optimization quite complicated. On a given column, one should first set the Gradient time to the longest tolerable and then set the temperature to the highest achievable with the instrument. Next, the flow rate should be optimized using a reasonable but arbitrary value of φfinal. Last, the final eluent strength should be adjusted so that the last solute elutes as close as possible to the Gradient time. We also develop an easily implemented, highly efficient, and effecti...
S D Findlay - One of the best experts on this subject based on the ideXlab platform.
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probing the limits of the rigid intensity shift model in differential Phase contrast scanning transmission electron microscopy
Physical Review A, 2018Co-Authors: L Clark, H G Brown, David M Paganin, Michael John Morgan, T Matsumoto, Naoya Shibata, Timothy Petersen, S D FindlayAbstract:The rigid-intensity-shift model of differential Phase contrast scanning transmission electron microscopy (DPC-STEM) imaging assumes that the Phase Gradient imposed on the probe by the sample causes the diffraction pattern intensity to shift rigidly by an amount proportional to that Phase Gradient. This behaviour is seldom realised exactly in practice. Through a combination of experimental results, analytical modelling and numerical calculations, we explore the breakdown of the rigid-intensity-shift behaviour and how this depends on the magnitude of the Phase Gradient and the relative scale of features in the Phase profile and the probe size. We present guidelines as to when the rigid-intensity-shift model can be applied for quantitative Phase reconstruction using segmented detectors, and propose probe-shaping strategies to further improve the accuracy.
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probing the limits of the rigid intensity shift model in differential Phase contrast scanning transmission electron microscopy
Physical Review A, 2018Co-Authors: L Clark, H G Brown, David M Paganin, Michael John Morgan, T Matsumoto, Naoya Shibata, Timothy Petersen, S D FindlayAbstract:The rigid-intensity-shift model of differential-Phase-contrast imaging assumes that the Phase Gradient imposed on the transmitted probe by the sample causes the diffraction pattern intensity to shift rigidly by an amount proportional to that Phase Gradient. This behavior is seldom realized exactly in practice. Through a combination of experimental results, analytical modeling and numerical calculations, using as case studies electron microscope imaging of the built-in electric field in a p-n junction and nanoscale domains in a magnetic alloy, we explore the breakdown of rigid-intensity-shift behavior and how this depends on the magnitude of the Phase Gradient and the relative scale of features in the Phase profile and the probe size. We present guidelines as to when the rigid-intensity-shift model can be applied for quantitative Phase reconstruction using segmented detectors, and propose probe-shaping strategies to further improve the accuracy.