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Modified physical optics algorithm for near field scattering

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Chinese Physics B 2018年第11期27卷 472-476页

作者：陈彬童创明 Air Force Engineering University Xi'an 710051 China

A novel modified physical optics algorithm is proposed to overcome the difficulties of near field scattering prediction for classical physical optics. The method is applied to calculating the near field radar cross section of electrically large objects by taking into account the influence of the distinct wave propagation vector, the near field Green function, and the antenna radiation pattern. By setting up local reference coordinates, each partitioned facet has its own distinct wave front curvature. The radiation gain for every surface element is taken into consideration based on the modulation of the antenna radiation pattern. The Green function is refined both in amplitude and phase terms and allows for near field calculation. The scattered characteristics of the near field targets are studied by numerical simulations. The results show that the approach can achieve a satisfactory accuracy.

关键词： physical optics scattering near field

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Applied Mathematics and Mechanics(English Edition) 2011年第12期32卷 1491-1504页

作者：张振华汪玉张立军袁建红赵海峰 Department of Ship and Ocean Engineering Naval University of Engineering Naval Academy of Armament

The final anomalous sag distortion of the ship girder subjected to the near field underwater explosion （undex） below the middle ship is studied. The sinking exercise of Spruance class destroyer DD973 sunk by one MK48 torpedo is first presented, and a simulation model is established. The exponential attenuation phase, the reciprocal attenuation phase, the post reciprocal attenuation phase, and the negative pressure phase of the undex load are precisely applied in this model. The fluid-solid interaction, the added water mass, the gravity, and the change of buoyancy are also taken into account. The similarity theory is then used to analyze the dynamic response of the ship girder. Similarity parameters and theory prediction formulae of the dynamic response of the ship girder are presented, The physical meaning and influences of these similarity parameters are analyzed.

关键词： underwater explosion (undex) ship girder near field anomalous response,similarity analysis

An Accurate near-field Distance Estimation Differential Algorithm

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Chinese Journal of Electronics 2022年第5期31卷 851-859页

作者： ZHAO Yan TAO Haihong CHANG Xin National Key Laboratory of Radar Signal Processing Xidian Univercity The 54th Research Institute China Electronics Technology Group Corporation School of Electronic Engineering Xidian University

The triangular geometry is the basis of near field array accurate distance estimation *** Fisher expression of traditional distance estimation is derived by utilizing the Taylor series. To improve convergence rate and estimation accuracy, a novel iterative distance estimation algorithm is proposed with differential equations based on the triangular geometry. Firstly, its convergence performance is analysed in detail. Secondly,the selection of the initial value and the number of iterations are respectively studied. Thirdly, compared with the traditional estimation algorithms by utilizing the Fisher approximation, the proposed algorithm has a higher convergence rate and estimation accuracy. Moreover, its pseudocode is presented. Finally, the experiment results and performance analysis are provided to verify the effectiveness of the proposed algorithm.

关键词： Distance estimation near field Fisher approximation Differential equations Taylor series expansion

Research on near field of Airborne Short Wave Antenna

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Research on Near Field of Airborne Short Wave Antenna

Symmetry selective directionality in near-field acoustics

1997 International Symposium on Electromagnetic Compatibility

作者： XUE Zhenghui GAO Benqing LIU Ruixiang LU Xin YANG Li Department of Electronic Engineering of Beijing Institute of Technology

ISBN: (纸本)0780336089

＜正＞The near field of a Boeing 707 320B aircraft excited by its short wave antenna has been calculated and analyzed using FDTD Method after modeling aircraft and short wave antenna by B-spline *** research can provide data for the further study of the short wave antenna’s impedance character、far field pattern and mutual interference between short wave communication and other electronic equipment,it can play an important role in aircraft EMC analysis and design.

关键词： finite difference time-domain analysis aircraft communication mobile antennas antenna radiation patterns electric impedance radiofrequency interference splines (mathematics) electromagnetic compatibility avionics airborne short wave antenna near field Boeing 707 320B aircraft FDTD method B-spline method impedance character far field pattern mutual interference short wave communication electronic equipment EMC analysis design

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National Science Review 2020年第6期7卷 1024-1035页

作者： Yang Long Hao Ge Danmei Zhang Xiangyuan Xu Jie Ren Ming-Hui Lu Ming Bao Hong Chen Yan-Feng Chen Center for Phononics and Thermal Energy Science China-EU Joint Center for Nanophononics Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology School of Physics Sciences and Engineering Tongji University Department of Materials Science and Engineering College of Engineering and Applied Sciences and National Laboratory of Solid State Microstructures Nanjing University Key Laboratory of Noise and Vibration Research Institute of Acoustics Chinese Academy of Sciences Collaborative Innovation Center of Advanced Microstructures Nanjing University Key Laboratory of Noise and Vibration Research Institute of Acoustics Chinese Academy of Sciences Beijing 100190 China and4Collaborative Innovation Center of Advanced Microstructures Nanjing University

Understanding unidirectional and topological wave phenomena requires the unveiling of intrinsic geometry and symmetry for wave dynamics. This is essential yet challenging for the flexible control of near-field evanescent waves, highly desirable in broad practical scenarios ranging from information communication to energy radiation. However, exploitations of near-field waves are limited by a lack of fundamental understanding about inherent near-field symmetry and directional coupling at sub-wavelengths, especially for longitudinal waves. Here, based on the acoustic wave platform, we show the efficient selective couplings enabled by near-field symmetry properties. Based on the inherent symmetry properties of three geometrically orthogonal vectors in near-field acoustics, we successfully realize acoustic Janus, Huygens,spin sources and quadrupole hybrid sources, respectively. Moreover, we experimentally demonstrate fertile symmetry selective directionality of those evanescent modes, supported by two opposite meta-surfaces. The symmetry properties of the near-field acoustic spin angular momenta are revealed by directly measuring local vectorial fields. Our findings advance the understanding of symmetries in near-field physics, supply feasible approaches for directional couplings, and pave the way for promising acoustic devices in the future.

关键词： acoustics near field symmetry

Study on the near field of the Semiconductor Laser by Using Scanning near field Optical Microscope

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Chinese Journal of Lasers 2000年第4期9卷 16-20页

作者： GAO Chunqing 1 RENG Norbert 2 ( 1 Optical Engineering Department, Beijing Institute of Technology, Beijing 100081, China 2 Laser und Medizin Technology gGmbH, Rudower Chaussee 6, D 12489 Berlin, Germany) 北京理工大学北京 Laser und Medizin-Technology gGmbH 德国

The near field of a semiconductor laser was measured by using a Scanning near field Optical Microscope (SNOM). The near field emission was recorded during the scanning of the fibre tip above the facet of the semiconductor laser at a distance less than 20 nm. By controlling the shear force the topography of the facet was recorded simultaneously. The waist radius, the divergence and the M 2 factor of the semiconductor laser were obtained by measuring the beam images in different positions along the propagation.

关键词： SNOM semiconductor laser near field

Distance dependence of atomic-resolution near-field imaging on α-Al2O3 （0001） surface with respect to surface photovoltage of silicon probe tip

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Nano Research 2016年第2期9卷 530-536页

作者： Junsuke Yamanishi Takashi Tokuyama Yoshitaka Naitoh Yan Jun Li Yasuhiro Sugawara Department of Applied Physics Graduate School of Engineering Osaka University 2-1 Yamada-oka Suita Osaka 565-0871 Japan

Recently, we achieved atomic-resolution optical imaging with near-field scanning optical microscopy using photon-induced force detection. In this technique, the surface photovoltage of the silicon-tip apex induced by the optical near field on the surface is measured as the electrostatic force. We demonstrated atomicresolution imaging of the near field on the α-Al2O3 （0001） surface of a prism. We investigated the spatial distribution of the near field by scanning at different tip-sample distances and found that the atomic corrugation of the near-field signal was observed at greater distances than that of the atomic force microscopy signal. As the tip-sample distance increased, the normalized signal-to-noise ratio of the near field is in a gradual decline almost twice that of the frequency shift （Δf）.

关键词： near-field scanning optical microscopy near field surface photovoltage ci-Al2O3 (0001) force detection

Reconstructing a complex field from a series of its near-field diffraction patterns

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Chinese Physics B 2012年第10期21卷 260-264页

作者：洪友丽张凯王志立朱中柱赵雪娇黄万霞袁清习朱佩平吴自玉 Beijing Synchrotron Radiation Facility Institute of High Energy PhysicsChinese Academy of Sciences National Synchrotron Radiation Laboratory University of Science and Technology of China

We propose a method for reconstructing a complex field from a series of its near-field diffraction *** method is based on the paraxial Fresnel diffraction equation without making further *** simulations are presented showing that a complex field can even be reconstructed with moderate qualities from its two near-field diffraction patterns and almost exact reconstructions can be obtained when three or more diffraction patterns are *** also show by numerical simulation that the correct diffraction distances can be recovered in case only coarsely measured values are *** method may be applied to phase imaging of weak-absorption objects.

关键词： phase imaging near field phase retrieval

near-field Loop Antenna for the UHF RFID Reader

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Journal of Electronic Science and Technology 2011年第3期9卷 256-260页

作者： Peng Yang Yan Li Li-Jun Jiang Feng Yang School of Electronic Engineering University of Electronic Science and Technology of China Chengdu 610054 China Department of Electrical and ElectronicEngineering University of Hong Kong Hong Kong China.

A loop antenna for near field readers is proposed. Through periodic interdigital capacitors, the phase of the current on the loop is compensated and kept in phase. Hence, a loop with a perimeter of one wavelength at 900 MHz achieves a uniform near magnetic field distribution inside the loop. A novel method is proposed to evaluate the performance of the coplanar waveguide （CPW） to coplanar stripline （CPS） transition, which is used as a balun for the feeding network in this paper. This loop antenna has a 70 MHz operating bandwidth and 12 cm maximum reading range when the output power is 24 dBm, which is suitable for most near field radio frequency identification （RFID） applications.

关键词： Index Terms--Loop antenna near field reader antenna radio frequency identification.