- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Dual-band System composed by a Photonics-based Radar and a Focal-Point/Cassegrain Parabolic Antenna
摘要： This work reports a dual-band radar system composed of a photonics-based transceiver and a unique dual-band antenna. The proposed antenna consists of an integration of conventional focal-point and Cassegrain parabolic antennas in the same structure, ensured by using a subreflector based on a frequency selective surface. Numerical and experimental results in terms of the antenna reflection coefficient, radiation pattern and gain are reported with excellent agreement over both frequency ranges. The innovative dual-band photonics-based radar transceiver operates simultaneously in the S- and X-bands. The radar system has been properly validated by multiple detections of helicopters and airplanes in real conditions.
关键词： radar,frequency selective surface,Antennas,dual-use radars
更新于2025-09-23 15:22:29
-
A 65 nm 19.1-to-20.4 GHz Sigma-Delta Fractional-N Frequency Synthesizer with Two-Point Modulation for FMCW Radar Applications
摘要： A 19.1-to-20.4 GHz sigma-delta fractional-N frequency synthesizer with two-point modulation (TPM) for frequency modulated continuous wave (FMCW) radar applications is presented. The FMCW synthesizer proposes a digital and voltage controlled oscillator (D/VCO) with large continuous frequency tuning range and small digital controlled oscillator (DCO) gain variation to support TPM. By using TPM technique, it avoids the correlation between loop bandwidth and chirp slope, which is beneficial to fast chirp, phase noise and linearity. The start frequency, bandwidth and slope of the FMCW signal are all reconfigurable independently. The FMCW synthesizer achieves a measured phase noise of ?93.32 dBc/Hz at 1MHz offset from a 19.25 GHz carrier and less than 10 μs locking time. The root-mean-square (RMS) frequency error is only 112 kHz with 94 kHz/μs chirp slope, and 761 kHz with a fast slope of 9.725 MHz/μs respectively. Implemented in 65 nm CMOS process, the synthesizer consumes 74.3 mW with output buffer.
关键词： FMCW radar,fractional-N,two-point modulation,CMOS,phase locked loop,frequency synthesizer
更新于2025-09-23 15:22:29
-
Semi-Automated Classification of Lake Ice Cover Using Dual Polarization RADARSAT-2 Imagery
摘要： Lake ice is a significant component of the cryosphere due to its large spatial coverage in high-latitude regions during the winter months. The Laurentian Great Lakes are the world’s largest supply of freshwater and their ice cover has a major impact on regional weather and climate, ship navigation, and public safety. Ice experts at the Canadian Ice Service (CIS) have been manually producing operational Great Lakes image analysis charts based on visual interpretation of the synthetic aperture radar (SAR) images. In that regard, we have investigated the performance of the semi-automated segmentation algorithm “glocal” Iterative Region Growing with Semantics (IRGS) for lake ice classification using dual polarized RADARSAT-2 imagery acquired over Lake Erie. Analysis of various case studies indicated that the “glocal” IRGS algorithm could provide a reliable ice-water classification using dual polarized images with a high overall accuracy of 90.4%. However, lake ice types that are based on stage of development were not effectively identified due to the ambiguous relation between backscatter and ice types. The slight improvement of using dual-pol as opposed to single-pol images for ice-water discrimination was also demonstrated.
关键词： RADARSAT-2,classification,lake ice,synthetic aperture radar
更新于2025-09-23 15:22:29
-
Spatial-Based Chipless RFID System
摘要： Conventional techniques in chipless RFID systems are incapable of fully overcoming the key challenges of modern identification applications, including high data capacity, low tag cost and reliable operation. The idea of electromagnetic (EM) imaging in chipless RFID systems is a promising technique that shows many advantages over other conventional approaches. This paper reviews conventional chipless RFID technology and provides a comprehensive analysis of advanced millimeter wave spatial-based (also known as image-based) chipless RFID systems with an optimized MIMO-SAR technique for high-resolution image acquisition and a quick reading process.
关键词： Multiple-input multiple-output (MIMO),Millimeter wave (mmwave),Chipless radio frequency identification (RFID),EM imaging,Virtual antenna array,Synthetic aperture radar (SAR)
更新于2025-09-23 15:22:29
-
Improved Method of Video Synthetic Aperture Radar Imaging Algorithm
摘要： Video synthetic aperture radar (ViSAR) is a novel imaging model to persistently surveil the region of interest by a series of consecutive images in real time. The formation time of one frame image, which can influence the image latency, is one of the key factors to realize ViSAR system. In general, the polar format algorithm (PFA) is preferred for ViSAR imaging. However, the 2-D resampling in the PFA has a large computation burden and is complex to realize in the real-time processing system. It has become the main obstacle to reduce image latency. Therefore, we derive four judgment criteria in this letter. According to these criteria, we propose the improved method of the PFA. Based on this method, the modified PFA can reduce the image formation time while guaranteeing the image quality. Simulation results are presented to validate the effectiveness of the improved method proposed in this letter.
关键词： judgment criteria,Improved method,video synthetic aperture radar (ViSAR),polar format algorithm (PFA)
更新于2025-09-23 15:22:29
-
77-GHz mmWave antenna array on liquid crystal polymer for automotive radar and RF front-end module
摘要： This paper introduces a low‐cost, high‐performance mmWave antenna array module at 77 GHz. Conventional waveguide transitions have been replaced by 3D CPW‐microstrip transitions which are much simpler to realize. They are compatible with low‐cost substrate fabrication processes, allowing easy integration of ICs in 3D multi‐chip modules. An antenna array is designed and implemented using multilayer coupled‐fed patch antenna technology. The proposed 16 × 16 array antenna has a fractional bandwidth of 8.4% (6.5 GHz) and a 23.6‐dBi realized gain at 77 GHz.
关键词： broadband transition,3D transition,mmWave antenna array,automotive radar module,proximity-coupled patch antenna
更新于2025-09-23 15:22:29
-
A new CFAR algorithm based on variable window for ship target detection in SAR images
摘要： Target detection in the multiscale situation where there exit multiple ship targets with different sizes is a challenging task due to the mismatch of the sizes of ship targets and fixed windows. A new constant false alarm rate (CFAR) algorithm based on variable window for ship target detection in SAR images is proposed. First, the multiscale local contrast measure is introduced to estimate the ship target size without any prior knowledge about ships. Second, the size of neighborhood area is adaptively set and a transform algorithm is designed to enhance the contrast between targets and background. Finally, CFAR detection is implemented by adopting variable window to gain the accurate ship targets. Experimental results indicate that the proposed algorithm has better performance compared with other CFAR detection algorithms.
关键词： Constant false alarm rate (CFAR),Ship target detection,Variable window,Synthetic aperture radar (SAR)
更新于2025-09-23 15:22:29
-
[IEEE 2018 IEEE 3rd International Conference on Signal and Image Processing (ICSIP) - Shenzhen, China (2018.7.13-2018.7.15)] 2018 IEEE 3rd International Conference on Signal and Image Processing (ICSIP) - Review of Research on Registration of SAR and Optical Remote Sensing Image Based on Feature
摘要： Synthetic Aperture Radar(SAR) and optical remote sensing image registration is the prerequisite for image fusion and it is of important theoretical significance and practical value. The image registration methods are mainly divided into the methods based on feature, the methods based on Gray-scale and others. This article systematically sorts out feature-based optical and SAR remote sensing image registration techniques, summarizes all types of image registration, points out their advantages and disadvantages and predicts the prospects of their future.
关键词： synthetic aperture radar(SAR),image registration,remote sensing,feature-based
更新于2025-09-23 15:22:29
-
Phasor Quaternion Neural Networks for Singular Point Compensation in Polarimetric-Interferometric Synthetic Aperture Radar
摘要： Interferograms obtained by synthetic aperture radar often include many singular points (SPs), which makes it difficult to generate an accurate digital elevation model. This paper proposes a filtering method to compensate SPs adaptively by using polarization and phase information around the SPs. Phase value is essentially related to polarization changes in scattering as well as propagation. In order to handle the polarization and phase information simultaneously in a consistent manner, we define a new number, phasor quaternion (PQ), by combining quaternion and complex amplitude, with which we construct the theory of PQ neural networks (PQNNs). Experiments demonstrate that the proposed PQNN filter compensates SPs very effectively. Even in the situations where the conventional methods deteriorate in their performance, it realizes accurate compensation, thanks to its good generalization characteristics in integrated Poincare-sphere polarization space and the complex-amplitude space. We find that PQNN is an excellent framework to deal with the polarization and phase of electromagnetic wave adaptively and consistently.
关键词： Complex-valued neural network (CVNN),phase singular point,polarimetric interferometric synthetic aperture radar (PolInSAR),quaternion neural network (QNN),digital elevation model (DEM)
更新于2025-09-23 15:22:29
-
[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 - An Tensor-Based Corn Mapping Scheme with Radarsat-2 Fully Polarimetric Images
摘要： As one of the most essential economic and industrial crops globally, corn holds a very important position in China’s agricultural industry. Corn mapping is one of the most concerned fields in agricultural surveillance. However, compared with the utilization of backscattering coefficients, the polarimetric information was not fully discussed in previous corn mapping researches. In this paper, we use the coherency matrix of mid to late term multi-temporal fully polarimetric synthetic aperture radar (FP SAR) data to discriminate corn cultivation areas. The tensor representation is adopted for PolSAR analysis, with the help of multilinear principal component analysis (MPCA) to reduce feature dimensions. The importance of polarimetric information is discussed. This paper illustrates that good corn discrimination could be achieved with only mid to late term FP SAR data.
关键词： corn mapping,synthetic aperture radar (SAR),decision tree,multi-temporal SAR,multilinear principal component analysis (MPCA),polarimetric SAR (PolSAR)
更新于2025-09-23 15:22:29