- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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[IEEE 2018 IEEE International Conference on Computational Electromagnetics (ICCEM) - Chengdu, China (2018.3.26-2018.3.28)] 2018 IEEE International Conference on Computational Electromagnetics (ICCEM) - Multiple Orbital Angular Momentum Vortex Electromagnetic Waves Multiplex Transmission and Demultiplex Reception Analysis
摘要： We investigated the multiplexing transmission and demultiplexing reception properties of vortex electromagnetic wave with multiple orbital angular momentum (OAM) modes. In this paper, a uniform circular array (UCA) antenna model at 10GHz is designed for generating multiple OAM modes vortex electromagnetic wave, and both the transmission characteristics, i.e., the field distribution in the space, and the reception characteristics are analyzed. The whole aperture sampling receiving (WASR) scheme is used for the reception. And the radius of the reception aperture that influences the multiple OAM modes demultiplex reception effects is analyzed. Some numerical calculation simulation experiments are performed and a simple expression is defined as mode percent for measuring the reception effects.
关键词： Demultiplex reception,UCA antenna,whole aperture sampling receiving (WASR),multiplex transmission,multiple OAM modes,vortex electromagnetic wave
更新于2025-09-10 09:29:36
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3-D Inverse Synthetic Aperture Ladar Imaging and Scaling of Space Debris Based on the Fractional Fourier Transform
摘要： The inverse synthetic aperture ladar (ISAL) is an important method for observation and imaging of space targets. Here, a 3-D ISAL imaging algorithm is proposed for spinning targets such as space debris. Since laser wavelength is 4–5 orders of magnitude smaller than that of microwave, the Doppler frequency caused by target motion is more pronounced in ISAL. Doppler frequency modulation rates can be estimated by the fractional Fourier transform with respect to azimuth slow time even when the rotation angle is small such that scattering centers do not migrate through a range cell. Then, slant range, Doppler frequency, and Doppler frequency modulation rates form a 3-D space. The angular velocity and the incident angle can be estimated by the position relationship between the scattering centers in two observations. After image scaling, the 3-D shape and size of the target can be obtained. The 3-D structure of the target in the simulation experiment is accurately reconstructed. Monte Carlo experiments are conducted to discuss the effect of the signal-to-noise ratio and observation time on the algorithm. Finally, the effectiveness and robustness of the algorithm are veri?ed.
关键词： space debris,3-D imaging,inverse synthetic aperture radar (ISAR),fractional Fourier transform (FrFT),laser radar
更新于2025-09-10 09:29:36
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High-Gain Electrically Large Air-Cavity-Backed Patch Antenna Element and Array
摘要： In this work, single high-gain patch antenna element with electrical large property (ELP) based on TM30 mode is presented. Stable field distribution of the TM30-mode is maintained by using one TE20-mode substrate integrated waveguide (SIW) slot-coupling feed structure. Furthermore, air-cavity-backed structure and metal pins are introduced to expand the antenna bandwidth. The ELP element resonates at 22GHz with simulated -10dB impedance bandwidth of 6.9% and maximum gain of 14.2 dBi. Then in order to correct the asymmetrical field distribution in TE20-mode SIW, differential feed technology is introduced in array design. The feeding network consists of two TE10-TE20 mode planar transducers and one anti-phase power divider. The working principle and design procedure of the ELP array are given in detail accordingly. Finally, a 2×2 ELP array is optimized and fabricated for verification. The measured results show that the array antenna has -10dB impedance bandwidth of 9% and maximum gain of 18.9 dBi. Furthermore, it owns merit of excellent radiation performance with high aperture efficiency of about 90%.
关键词： high-gain,Array antenna,high-order mode,millimeter-wave,high-aperture efficiency,mode-transducer,electrically large property (ELP),differential feeding network
更新于2025-09-10 09:29:36
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Airship Based MIMO Radar: Analysis of Imaging and Interferometric Performances
摘要： We study the imaging and interferometric performances of a MIMO radar on board of an airship as alternative to airborne and spaceborne SAR remote sensing techniques. Four different MIMO radar arrays are designed working in L, C, X and Ku frequency bands. A frequency bandwidth of 250 MHz has been considered for the MIMO radars. The spatial resolution is 0.6 m in range and 0.3 degree in azimuth. The imaging and interferometric performances of the MIMO radar are analyzed in terms of the airship stability. A synthetic raw data set is generated assuming a target deployed on a flat area at different azimuth angle. This MIMO imaging solution is intended for continuous imaging over an area of interest.
关键词： Synthetic Aperture Radar (SAR),interferometry,MIMO radar,airship,Persistent imaging
更新于2025-09-10 09:29:36
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Marine Oil Slicks Quantification From L-band Dual-Polarization SAR Imagery
摘要： We show, using simple physical models, that a quantitative estimation of the volume fraction of marine oil slicks can be achieved from dual-polarization synthetic aperture radar (SAR) imagery. Volume fraction, which quantifies the proportion of seawater in oil in the case of a mixture, depends primarily on volume scattering mechanisms and is inferred from the polarization ratio in the L-band. A quantification algorithm is derived, namely, the volume fraction estimation algorithm that is applied to two experimental data sets acquired in the Mediterranean Sea during the POLLUPROOF’2015 exercise and in the North Sea during the NOFO’2015 experiment using the Office National d’études et de Recherches Aérospatiales airborne L-band SETHI system. The resulting volume fraction maps of the quantification method are presented and discussed, opening new perspectives for marine oil slicks monitoring by means of dual-polarization SAR imagery.
关键词： L-band,ocean radar sensing,quantification,Complex permittivity,volume fraction,dual-polarization synthetic aperture radar (SAR),marine oil slick
更新于2025-09-10 09:29:36
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[IEEE 2018 15th European Radar Conference (EuRAD) - Madrid, Spain (2018.9.26-2018.9.28)] 2018 15th European Radar Conference (EuRAD) - Simulation of Near Field RCS to Reproduce Measurement Condition
摘要： Different approaches are presented to simulate the near field Radar Cross Section (RCS) of a perfectly conducting electrically large object. This type of environment is usually found in measurements at large anechoic chambers where the far field condition cannot be achieved, making it impossible to approximate the incident field by a planewave. Each approach will be implemented with Physical Optics (PO) for extremely large targets and an accelerated version of the Method of Moments for moderately large objects. The fast MoM method are either the Multilevel Adaptive Cross Approximation (MLACA) for an iterative solution or the Multiscale Compressed Block Decomposition (MSCBD) for a direct solution. This development and the performed simulations have been done with CAPITOLE-RCS commercial software developed by NEXIO.
关键词： physical optics,method of moments,radar cross-sections,inverse synthetic aperture radar,Numerical simulation,anechoic chambers
更新于2025-09-10 09:29:36
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OPTIMIZATION OF MICROMACHINED MILLIMETER-WAVE PLANAR SILICON LENS ANTENNAS WITH CONCENTRIC AND SHIFTED MATCHING REGIONS
摘要： This paper presents a study of planar silicon lens antennas with up to three stepped-impedance matching regions. The e?ective permittivity of the matching regions is tailor-made by etching periodic holes in the silicon substrate. The optimal thickness and permittivity of the matching regions were determined by numerical optimization to obtain the maximum wideband aperture e?ciency and smallest side-lobes. We introduce a new geometry for the matching regions, referred to as shifted matching regions. The simulation results indicate that using three shifted matching regions results in twice as large aperture e?ciency as compared to using three conventional concentric matching regions. By increasing the number of matching regions from one to three, the band-averaged gain is increased by 0.3 dB when using concentric matching regions, and by 3.7 dB when using shifted matching regions, which illustrates the advantage of the proposed shifted matching region design.
关键词： side-lobes,planar silicon lens antennas,shifted matching regions,aperture efficiency,stepped-impedance matching regions
更新于2025-09-10 09:29:36
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Monitoring Coastal Reclamation Subsidence in Hong Kong with Distributed Scatterer Interferometry
摘要： Land subsidence has been a signi?cant problem in land reclaimed from the sea, and it is usually characterized by a differential settlement pattern due to locally unconsolidated marine sediments and ?ll materials. Time series Synthetic Aperture Radar Interferometry (InSAR) techniques based on distributed scatterers (DS), which can identify sufficient measurement points (MPs) when point-wise radar targets are lacking, have great potential to measure such differential reclamation settlement. However, the computational time cost has been the main drawback of current distributed scatterer interferometry (DSI) for its applications compared to the standard PSI analysis. In this paper, we adopted an improved DSI processing strategy for a fast and robust analysis of land subsidence in reclaimed regions, which is characterized by an integration of fast statistically homogeneous pixel selection based (FaSHPS-based) DS detection and eigendecomposition phase optimization. We demonstrate the advantages of the proposed DSI strategy in computational efficiency and deformation estimation reliability by applying it to two TerraSAR-X image data stacks from 2008 to 2009 to retrieve land subsidence over two typical reclaimed regions of Hong Kong International Airport (HKIA) and Hong Kong Science Park (HKSP). Compared with the state-of-the-art DSI methods, the proposed strategy significantly improves the computational efficiency, which is enhanced approximately 30 times in DS identification and 20 times in phase optimization. On average, the DSI strategy results in 7.8 and 3.7 times the detected number of MPs for HKIA and HKSP with respect to persistent scatter interferometry (PSI), which enables a very detailed characterization of locally differential settlement patterns. Moreover, the DSI-derived results agree well with the levelling survey measurements at HKIA, with a mean difference of 1.87 mm/yr and a standard deviation of 2.08 mm/yr. The results demonstrate that the proposed DSI strategy is effective at improving target density, accuracy and efficiency in monitoring ground deformation, particularly over reclaimed coastal areas.
关键词： ef?ciency,Hong Kong,Synthetic Aperture Radar Interferometry (InSAR),distributed scatterers,reclamation subsidence,persistent scatterers
更新于2025-09-10 09:29:36
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[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris, France (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Study of Keysight 3458A Temperature Coefficient for Different Aperture Times in DCV Sampling Mode
摘要： A study of DCV sampling mode Keysight 3458A digital multimeter (DMM) temperature coefficient is presented. For different DMMs, a set of digital measurements at different temperatures and aperture times has been performed, to establish DMMs gain variation with temperature. Results confirm the existence of two different temperature coefficients, for high-resolution and high-speed stages. While for the first one values in the range of 0.1 μV/VoC are obtained, for high speed stage values can be in the order of 10 μV/VoC, which should be taken into account for its compensation in high accuracy measurement.
关键词： Precision measurement,Sampling,Analog-digital conversion,Temperature coefficient,Aperture time
更新于2025-09-10 09:29:36
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[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris, France (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Time Latency of DC Input Path for 3458A Sampling Multimeter
摘要： The Keysight 3458A is a common digitizer because of the great accuracy and small integration time. The bandwidth of its DC input path varies depending on the magnification of input amplifier of different ranges, which causes time latency of input signal. A method to measure the latency based on aperture time is introduced. When the aperture approximately equals to the period of the signal under test, extremum of sampling value reflects signal's initial phase. Experiments at 1V and 10V ranges with input signals of 25kHz and 50kHz were carried out and the time latency were measured. Then the bandwidth were calculated which were the same of about 120kHz for these two ranges.
关键词： phase shift,time latency,synchronous sampling,bandwidth,Aperture time
更新于2025-09-10 09:29:36