- 标题
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- 实验方案
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Multiplexed OAM Wave Communication with Two-OAM-Mode Antenna Systems
摘要： In order to improve channel capacity, waves carrying orbital angular momentum (OAM) in communication systems have attracted much attention. A two-OAM-mode antenna system, which works at 2.4 GHz, is proposed in this paper. And a signal transmission experiment is performed based on a pair of the proposed antenna systems. The proposed antenna system, which has the planar structure, is composed of two patch antenna arrays, two feeding networks and one common ground plane. Then, re?ection coef?cients, transmission coef?cients, radiation patterns and phase distributions of the proposed antenna system are measured and the measurement results verify the effectiveness of this antenna system in generating two OAM modes (OAM mode 1 and OAM mode 2). The measurement results are in good agreement with the simulation results. Then the signal transmission system is built based on a pair of the proposed antenna systems. Isolation between OAM mode 1 transceiver channel and OAM mode 2 transceiver channel is more than 20 dB. Video signals modulated by FBMC (Filter Bank Multicarrier) are de-modulated simultaneously at the receiving terminal. It means that the two-OAM-mode antenna system has the potential to enhance the channel capacity.
关键词： antenna array,FBMC,Orbital angular momentum (OAM),patch antenna
更新于2025-09-04 15:30:14
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[IEEE 2018 Cross Strait Quad-Regional Radio Science and Wireless Technology Conference (CSQRWC) - Xuzhou (2018.7.21-2018.7.24)] 2018 Cross Strait Quad-Regional Radio Science and Wireless Technology Conference (CSQRWC) - Study of Propagation of Airy Array Vortex Beams in Turbulent Atmosphere
摘要： A circular phased-locked Airy beam array carrying orbital angular momentum (OAM) propagating through turbulent atmosphere is investigated in detail. The results testify that the OAM modes generated by the array are closely associated with the number of beamlets, requiring the number of beamlets at least twice more than the values of the OAM signal precisely. Furthermore, through multiple-phase-screen simulations, it is shown that the anti-jamming performance of an Airy beam array is significantly enhanced.
关键词： Atmospheric optics,Atmospheric propagation,Airy array vortex beam
更新于2025-09-04 15:30:14
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Remote Sensing Using VNIR/SWIR Dispersive Imaging Spectrometers: Historical Development, Current State-of-the-Art, and Furture Trends
摘要： The development of remote sensing using an imaging spectrometer is traced from its origins to the current highly performing spectral sensors. The advancement of the technology has primarily been driven by novel optical designs and focal plane array development. Current state-of-the-art dispersive sensors, employing innovative grating or prism arrangements, operate at low F-numbers while maintaining a high degree of aberration control. These challenging designs have been implemented in hardware with alignment tolerances on the order of microns. The application of imaging spectrometers to science problems that require highly accurate radiometry necessitates new characterization approaches that combine state-of-the-art radiometric sources and detailed sensor models. Future challenges are to reduce the size, weight, and power requirements while maintaining the performance of current systems.
关键词： VNIR/SWIR,optical designs,remote sensing,imaging spectrometer,focal plane array
更新于2025-09-04 15:30:14
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Sensor Array Design Through Submodular Optimization
摘要： We consider the problem of far-field sensing by means of a sensor array. Traditional array geometry design techniques are agnostic to prior information about the far-field scene. However, in many applications such priors are available and may be utilized to design more efficient array topologies. We formulate the problem of array geometry design with scene prior as one of finding a sampling configuration that enables efficient inference, which turns out to be a combinatorial optimization problem. While generic combinatorial optimization problems are NP-hard and resist efficient solvers, we show how for array design problems the theory of submodular optimization may be utilized to obtain efficient algorithms that are guaranteed to achieve solutions within a constant approximation factor from the optimum. We leverage the connection between array design problems and submodular optimization and port several results of interest. We demonstrate efficient methods for designing arrays with constraints on the sensing aperture, as well as arrays respecting combinatorial placement constraints. This novel connection between array design and submodularity suggests the possibility for utilizing other insights and techniques from the growing body of literature on submodular optimization in the field of array design.
关键词： Array design,submodular optimization,far field sensing
更新于2025-09-04 15:30:14
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Unit Circle Rectification of the Minimum Variance Distortionless Response Beamformer
摘要： The sample matrix inversion (SMI) beamformer implements Capon’s minimum variance distortionless (MVDR) beamforming using the sample covariance matrix (SCM). In a snapshot limited environment, the SCM is poorly conditioned resulting in a suboptimal performance from the SMI beamformer. Imposing structural constraints on the SCM estimate to satisfy known theoretical properties of the ensemble MVDR beamformer mitigates the impact of limited snapshots on the SMI beamformer performance. Toeplitz recti?cation and bounding the norm of weight vector are common approaches for such constraints. This paper proposes the unit circle recti?cation technique which constrains the SMI beamformer to satisfy a property of the ensemble MVDR beamformer: for narrowband planewave beamforming on a uniform linear array, the zeros of the MVDR weight array polynomial must fall on the unit circle. Numerical simulations show that the resulting unit circle MVDR (UC MVDR) beamformer frequently improves the suppression of both discrete interferers and white background noise compared to the classic SMI beamformer. Moreover, the UC MVDR beamformer is shown to suppress discrete interferers better than the MVDR beamformer diagonally loaded to maximize the signal-to-interference-plus-noise ratio.
关键词： unit circle,Capon beamformer,array polynomial,minimum variance distortionless response (MVDR),Adaptive beamformer (ABF)
更新于2025-09-04 15:30:14
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Colorimetric Sensor Array for Monitoring CO and Ethylene
摘要： Developing miniaturized and inexpensive detectors remains an important and practical goal for field-deployable monitoring of toxic gases and other bioactive volatiles. CO (a common toxic pollutant) and ethylene (the phytohormone primarily responsible for fruit ripening) share the capability of strong back-π-bonding to low-oxidation-state metal ions, which has proved important in the development of metal-ion-based sensors for these gases. We report herein cumulative colorimetric sensor arrays based on Pd(II)-silica porous microsphere sensors and their application as an optoelectronic nose for rapid colorimetric quantification of airborne CO and ethylene. Quantitative analysis of two gases was obtained in the range of 0.5 to 50 ppm with detection limits at the sub-parts-per-million level (～0.4 ppm) after 2 min of exposure and ～0.2 ppm after 20 min (i.e., <0.5% of the permissible exposure limit for CO and <10% of the ethylene concentration needed for fruit ripening). We further validate that common potential interfering agents (e.g., changes in humidity or other similar air pollutants such as NOx, SO2, H2S, or acetylene) are not misidentified with CO or ethylene. Finally, the sensor is successfully used for the quantification of ethylene emitted from ripening bananas, demonstrating its potential applications in the monitoring of fruit ripening during storage.
关键词： Pd(II)-silica porous microsphere sensors,CO,ethylene,colorimetric sensor array,optoelectronic nose
更新于2025-09-04 15:30:14
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Efficient bifunctional vanadium doped Ni3S2 nanorod array for overall water splitting
摘要： Electrochemical water splitting, allowing energy conversion from renewable resources into non-polluting chemical fuels, is vital in the future sustainable energy system, and great efforts have been paid on developing efficient and cheap bifunctional electrocatalysts. Herein we report a bifunctional vanadium doped Ni3S2 nanorod array electrode for overall water splitting in alkaline media. To afford a catalytic current of 10 mA cm-2, the designed V-Ni3S2 electrode only requires the overpotentials of 133 mV for hydrogen evolution and 148 mV for oxygen generation, meanwhile showing high long-term stability. The excellent catalytic properties are assigned to the V dopants and geometric advantages of nanorod array. The V-Ni3S2 electrodes are simultaneously utilized as cathode and anode in one two-electrode cell to function overall water splitting, exhibiting a cell voltage of 1.421 V at 10 mA cm-2. The water splitting in this cell can also be feasibly driven by a single-cell AA battery (1.5 V). Our report shows substantial advancement in the exploration of efficient bifunctional electrocatalysts for water splitting.
关键词： bifunctional electrocatalysts,water splitting,nanorod array,alkaline media,vanadium doped Ni3S2
更新于2025-09-04 15:30:14