- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
[IEEE 2018 IEEE 5G World Forum (5GWF) - Silicon Valley, CA, USA (2018.7.9-2018.7.11)] 2018 IEEE 5G World Forum (5GWF) - Evaluating Power Density for 5G Applications
摘要： The next generation of wireless 5G technology is being continuously designed to meet the growing demand from different industries for more data, more devices, higher speed, and improved operational efficiency. While mmWave bands offer much higher bandwidths, they are subject to higher signal losses when compared to the lower frequency bands currently used for wireless technologies. As such, the industries involved require evolutionary methodologies for the thorough evaluation of 5G mobile devices. The authors offer an advanced near-field measurement technique as a solution for robust assessment of device performance. This novel method introduces the spatial vector evaluation of both electric E and magnetic H fields through the cross-detection of their interaction. Based in terms of the Poynting vector theorem, this two-probe technique provides a steady measurement-based orientation for research within the rapidly changing conditions of the mmWave environment.
关键词： phase shift,beamforming,5G,field patterns,E field,H field,Poynting vector,power density,near-field measurement
更新于2025-09-10 09:29:36
-
Passive localization and classification of mixed near-field and far-field sources based on high-order differencing algorithm
摘要： A novel method called high-order differencing algorithm (HODA) is presented for localization of mixed sources. Five special cumulant matrices are constructed. The first one only contains the angle information. By modifying its rank and using an ESPRIT-like approach, the initial DOA set (IDOAS) is formed. The four others, pairwise, contain common far-field information. By two differencing operations, the far-field information is eliminated, and the difference cumulant matrices (DCMs) are obtained. After the rank modification is executed, the DCMs are reconstructed. By applying an ESPRIT-like approach to them, electrical angles are extracted. The extracted data is compared with IDOAS to obtain valid information of near-field sources (NFSs). A mechanism called kurtosis testing algorithm (KTA) is presented for identifying far-field sources (FFSs). KTA is able to identify even those FFSs that are located at the same angle with NFSs. To control the error of statistical differencing, an appropriate number of snapshots is considered. Analyses show that HODA prevents aperture loss; it does not require pairing, knowing the number of NFSs or FFSs, and heavy searches. The results confirm its good performance in terms of classification, the correct estimation of sources with different fields and the same DOAs, estimation accuracy and computational complexity.
关键词： Multiple mixed near-field and far-field sources,Proper number of snapshots,High-order differencing
更新于2025-09-10 09:29:36
-
Aggregation States of Organic Dye Molecules in Organic – Inorganic Hybrid Films Studied by Near-Field and Far-Field Fluorescence Spectroscopy
摘要： Near-field fluorescence spectroscopy in conjunction with far-field fluorescence and Raman spectroscopy has been applied to investigate the aggregation states of cyanine dye of 2-[5-(1,3-Dihydro-3,3-dimethyl-1-octadecyl-2H-indol-2-ylidene)-1,3-pentadienyl]-3,3-dimethyl-1-octadecyl-3H-indolium perchlorate (NK3175) molecules in the depth direction, from the nanometer-scale top surface to the bulk, in the hybrid films consisted of NK3175 and a clay compound (SWN). The far-field Raman spectra reveal that these hybrid films contained both NK3175 molecules which did not take part in the adsorption and those adsorbed on SWN. The near-field photoluminescence (PL) spectra in the outermost surface within ca. 30 nm exhibit a significant blue shift for the hybrid films as compared to their respective PL spectra in the bulk, implying that the top surface of these hybrid films becomes more polar and/or rigid in terms of the microenvironment around NK3175 molecules compared to the bulk of them, in contrast to the case for the other hybrid film which was prepared by the alternative method. These results provide new information on the aggregation states of organic dye molecules not only in the bulk but in the nanometer-scale top surface of organic-inorganic hybrid systems.
关键词： far-field fluorescence,Raman spectroscopy,organic-inorganic hybrid films,aggregation states,Near-field fluorescence spectroscopy,cyanine dye
更新于2025-09-10 09:29:36
-
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
-
[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) - Specific Excitation Conditions Achieved by Near Field Source in EM Analysis
摘要： A simple preprocessing of providing specific incident conditions for the structures that work with antenna array is proposed in this paper. In lots of electromagnetic (EM) systems, such as antenna-radome system, antenna array always works with other structures. To figure out the EM performance of these kinds of structures, specific excitation condition is needed. Based on Huygens-Fresnel and superposition principles, instead of real-world antenna array modeling, near field source is used as the excitation source. Using this method, prescribed incident conditions can be achieved easily. Numerical results show that the strategy of the proposed preprocessing has a capability of good feasibility and the EM analysis efficiency can be improved.
关键词： large-scale antenna array,near field source,specific excitation condition,radome
更新于2025-09-10 09:29:36
-
Surface plasmon-enhanced near-field thermal rectification in graphene-based structures
摘要： We propose a thermal rectification structure composed of InSb and graphene-coated 3C-SiC separated by a nanoscale vacuum gap. To obtain an obvious thermal rectification effect, the permittivities of these materials are all considered to be temperature-dependent. Numerical calculations based on fluctuation electrodynamics reveal that the introduction of graphene into the structure enhances significantly near-field radiative heat flux and thermal rectification efficiency owing to the strong coupling of surface plasmon-polaritons between InSb and graphene. In general, the rectification efficiency above 60% can be maintained for the vacuum gap less than 70 nm. The rectification efficiency exceeding 95% is realized for a vacuum gap of 10 nm and a chemical potential of 0.1 eV. Increasing the emitter’s temperature leads to the drastic increase of the rectification efficiency in a wider temperature range. A lower chemical potential seems more favorable to raising rapidly the rectification efficiency. The above results might be helpful in designing a thermal diode with higher efficiency and wider vacuum gap.
关键词： near-field radiative heat transfer,thermal rectification,InSb,surface plasmon-polaritons,graphene,3C-SiC
更新于2025-09-10 09:29:36
-
PLANAR PHASED ARRAY CALIBRATION BASED ON NEAR-FIELD MEASUREMENT SYSTEM
摘要： Matrix method for phased array calibration is an excitation reconstruction method by solving the linear equations based on the linear relationship between the measured near-field data and element excitations. In this paper, we propose a modified matrix method, in which the phased array model is simplified, to measure the element excitations of planar phased array. Our method reduces measurement time greatly at the cost of introducing some calibration errors. The introduced calibration errors can be minimized with the array excitation strategy proposed in this paper. Experimental results validate the effectiveness of our methods in calibrating planar phased arrays.
关键词： excitation reconstruction,near-field measurement,phased array calibration,matrix method
更新于2025-09-10 09:29:36
-
[IEEE 2018 International Conference on Electromagnetics in Advanced Applications (ICEAA) - Cartagena des Indias, Colombia (2018.9.10-2018.9.14)] 2018 International Conference on Electromagnetics in Advanced Applications (ICEAA) - A Low-Profile, Planar, Power-Efficient 2D Beam-Steering Antenna Technology
摘要： The paper explains a recently demonstrated 2D beam-steering antenna technology and its potential to develop a low-cost communication-on-the-move (COTM) terminal antenna. A low-cost COTM antenna is critical for receiving TV and internet via existing geostationary and upcoming low-earth-orbit (LEO) satellite constellations. The new beam-steering technology is based on near-field phase transformation and its working is verified by a prototype design reported recently. Performance indicators of the prototype are compared here with some commercially available COTM terminal antennas. A fully passive design, low-profile, low power requirements, and simple design configuration give the new steering antenna a competitive advantage over existing COTM terminal antennas from KYMETA and ThinKom.
关键词： low-earth-orbit (LEO) satellite,communication-on-the-move (COTM),low-profile,beam-steering antenna,near-field phase transformation
更新于2025-09-10 09:29:36
-
In Nano, Volume 12, Issue 11
摘要： Nanoprobes have become critical components of the many near-field imaging techniques developed over the past decade. These tools are typically constructed by integrating nanostructures on the tip of an optical fiber, for example, by coating them with an ultrathin layer of metal; etching with plasmonic nanoantennas; or attaching them with a single gold nanorod, semiconductor nanowire, metal nanoparticle, or photonic crystal nanocavity. The optical resonances of these materials to be concentrated into a confined region, enable light illuminating samples with nanometer resolution. However, these nanostructures are usually made with noble metals or semiconductors that lack biocompatibility and can easily rupture cells when interfacing with them. In addition, their preparation often requires sophisticated nanofabrication processes and electrochemical reactions. To avoid these issues, Li et al. (DOI: 10.1021/acsnano.8b05235) created nanoprobes made of living cells. The researchers made these tools by inserting a tapered fiber light source into a mixture of yeast and Lactobacillus acidophilus cells. Using light the researchers captured a single yeast cell onto its tip. Light conducted through that cell acted as a subsequent trapping laser beam to secure a string of connected L. acidophilus cells on top of the yeast cell. Tests showed that these nanoprobes could be used for near-field scanning imaging with a subwavelength spatial resolution to illuminate leukemia cells stained with green fluorescent protein in blood. The nanoprobes also demonstrated flexibility and deformability, bending when they contacted cells instead of rupturing them. The authors suggest that these living nanoprobes could find relevant applications in biosensing and imaging.
关键词： nanoprobes,imaging,living cells,near-field imaging,biosensing
更新于2025-09-10 09:29:36
-
Synthesis Algorithm for Near-Field Power Pattern Control and Its Experimental Verification via Metasurfaces
摘要： Antennas and metasurfaces have enabled a number of far-field manipulation functions. According to the addition theorem of multipoles, near fields have richer spatial spectra than far fields, hence in the near-field region it is easier to achieve complex manipulations on field distributions. In this work, an algorithm is presented to synthesize the near fields of source arrays. Given target distributions of near-field intensities and also predefined source magnitudes, the algorithm will find the needed source phases, which can then be applied on active antenna arrays and passive metasurfaces to induce the target distribution of fields. The algorithm adopts the dyadic Green’s function as the propagator, hence it naturally takes account of the near-field and vector properties of electromagnetic fields. As typical application of the algorithm, an example is given to obtain the excitation phases of a dipole array, which is then physically imitated by a coding metasurface. Experimental measurement is performed and the result proves the validity of the algorithm. From the perspective of information metasurface, the algorithm finds the phase-coding pattern of matesurface to achieve specific functions.
关键词： near-field control,Antenna pattern synthesis,computer-generated holography,phase coding,metasurface
更新于2025-09-10 09:29:36