- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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A High-Resolution 220-GHz Ultra-Wideband Fully Integrated ISAR Imaging System
摘要： In this paper, an ultra-wideband fully integrated imaging radar at sub-terahertz (sub-THz) frequencies is presented, which demonstrates a fine lateral resolution without using any focal lens/mirror. We have achieved a lateral resolution of 2 mm for an object at 23-cm distance as well as a range resolution of 2.7 mm. To achieve the decent range resolution, in a frequency modulation continuous wave radar configuration, a state-of-the-art chirp bandwidth (BW) of 62.4 GHz at a center frequency of 221.1 GHz is generated and efficiently radiated. We have presented a design technique for the optimal design of the passive embedding around the core transistor to maximize the tuning BW of the voltage controlled oscillator. At the receiver side, to maximize the intermediate frequency level, a subharmonic mixer is utilized, which is designed for the lowest conversion loss. Finally, to obtain the fine lateral resolution, we have implemented near-field beamforming algorithm based on the inverse synthetic aperture radar (ISAR) systems. The synthesized beamwidth is less than 0.5°; hence, high-resolution images are reconstructed. The system is fabricated in a 55-nm BiCMOS process. To the best of our knowledge, this is the first imaging radar at THz/sub-THz frequencies, which utilizes ISAR to achieve a high lateral resolution while the radar system is fully integrated.
关键词： ultra-wideband,Frequency modulation continuous wave (FMCW),remote sensing,THz,radar,sub-terahertz (sub-THz),oscillator,inverse synthetic aperture radar (ISAR),plane wave
更新于2025-09-23 15:21:21
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Wide-Angle, Ultra-Wideband ISAR Imaging of Vehicles and Drones
摘要： In-situ, wide-angle, and ultra-wideband inverse synthetic aperture radar (ISAR) imaging of vehicles and drones is demonstrated using a portable ultra-wideband radar. In order to form well-focused ISAR images, motion compensation is performed before applying the k-space imaging algorithm. While the same basic motion compensation methodology is applied to both types of targets, a more complex motion model is needed to better capture the ?ight path of the drone. The resulting ISAR images clearly show the geometrical outline of the targets and highlight locations of prominent backscattering. The ISAR images are also assessed against images generated through instrumented targets or laboratory measurements, and the image quality is shown to be comparable.
关键词： ultra-wideband,radar imaging,vehicles,radar measurements,drones,inverse synthetic aperture radar
更新于2025-09-23 15:21:01
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Bayesian High Resolution Range Profile Reconstruction of High-Speed Moving Target From Under-Sampled Data
摘要： Obtained by wide band radar system, high resolution range profile (HRRP) is the projection of scatterers of target to the radar line-of-sight (LOS). HRRP reconstruction is unavoidable for inverse synthetic aperture radar (ISAR) imaging, and of particular usage for target recognition, especially in cases that the ISAR image of target is not able to be achieved. For the high-speed moving target, however, its HRRP is stretched by the high order phase error. To obtain well-focused HRRP, the phase error induced by target velocity should be compensated, utilizing either measured or estimated target velocity. Noting in case of under-sampled data, the traditional velocity estimation and HRRP reconstruction algorithms become invalid, a novel HRRP reconstruction of high-speed target for under-sampled data is proposed. The Laplacian scale mixture (LSM) is used as the sparse prior of HRRP, and the variational Bayesian inference is utilized to derive its posterior, so as to reconstruct it with high resolution from the under-sampled data. Additionally, during the reconstruction of HRRP, the target velocity is estimated via joint constraint of entropy minimization and sparseness of HRRP to compensate the high order phase error brought by the target velocity to concentrate HRRP. Experimental results based on both simulated and measured data validate the effectiveness of the proposed Bayesian HRRP reconstruction algorithm.
关键词： inverse synthetic aperture radar (ISAR) imaging,entropy minimization,Newton method,variational Bayesian inference,High resolution range profile (HRRP),under-sampled data,velocity estimation
更新于2025-09-23 15:21:01
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Attitude Estimation for Space Targets by Exploiting the Quadratic Phase Coefficients of Inverse Synthetic Aperture Radar Imagery
摘要： This paper proposes a novel approach to interpreting the satellite attitude based on inverse synthetic aperture radar (ISAR) images. In the conventional viewpoint, quadratic and higher order phase terms of ISAR imagery are regarded as negative factors causing the defocusing phenomenon. In this paper, we introduce how to apply quadratic phase coefficients to estimate target attitude from the ISAR imagery. A geometric projection model of ISAR imaging is built according to radar line of sight, and an explicit expression is also derived to connect target attitude parameters and the image defocusing property. With the accommodation of Broyden–Fletcher–Goldfarb–Shanno algorithm, spatial-variant quadratic phase coefficients together with attitude parameters are determined by an image contrast maximization. We also extend the proposed algorithm to multistatic ISAR applications, where the quadratic phase information lying in simultaneous multistatic ISAR images can be mined to enhance the performance of target attitude estimation. Experimental results illustrate the feasibility of the proposed algorithm.
关键词： multistatic ISAR,inverse synthetic aperture radar (ISAR) imaging,Attitude estimation,imaging geometry analysis,image refocusing
更新于2025-09-19 17:15:36
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High-resolution ISAR imaging of fast rotating targets based on pattern-coupled Bayesian strategy for multiple measurement vectors
摘要： Very high resolution inverse synthetic aperture radar (ISAR) imaging of fast rotating targets is a complicated task. There may be insufficient pulses or may introduce migration through range cells (MTRC) during the coherent processing interval (CPI) when we use the conventional range Doppler (RD) ISAR technique. With compressed sensing (CS) technique, we can achieve the high-resolution ISAR imaging of a target with limited number of pulses. Sparse representation based method can achieve the super resolution ISAR imaging of a target with a short CPI, during which the target rotates only a small angle and the range migration of the scatterers is small. However, traditional CS-based ISAR imaging method generally faced with the problem of basis mismatch, which may degrade the ISAR image. To achieve the high resolution ISAR imaging of fast rotating targets, this paper proposed a pattern-coupled sparse Bayesian learning method for multiple measurement vectors, i.e. the PC-MSBL algorithm. A multi-channel pattern-coupled hierarchical Gaussian prior is proposed to model the pattern dependencies among neighboring range cells and correct the MTRC problem. The expectation-maximization (EM) algorithm is used to infer the maximum a posterior (MAP) estimate of the hyperparameters. Simulation results validate the effectiveness and superiority of the proposed algorithm.
关键词： Multiple measurement vectors (MMV),Fast rotating target,Inverse synthetic aperture radar (ISAR),Migration through range cells (MTRC),Pattern-coupled hierarchical model
更新于2025-09-11 14:15:04
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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 - Research Into Sar Imaging of Moving Ship Target Based on Isar Technology
摘要： The ship targets affected by sea conditions and other environment factors have complex non-cooperation movement, which cause serious defocusing phenomena in high resolution space-borne SAR images. In this paper, a novel ISAR-based imaging algorithm for moving ship target is presented. Firstly, the spatial geometric model of space-borne SAR is given, and the motorial characteristics of moving ship target are analyzed. Then, a novel imaging algorithm is derived, where the range alignment is solved by minimum information entropy criterion, and the accurate focusing is achieved through inverse SAR (ISAR) processing. Experiments based on the simulation and real data of TerraSAR-X are performed to validate the presented algorithm.
关键词： Motion compensation,Inverse Synthetic Aperture Radar(ISAR),Radar imaging,Minimum entropy,Moving Ship Target
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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[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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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
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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 - High Quality Isar Imaging for Target of Arbitrary Trajectory Based on Back Projection and Particle Swarm Optimization
摘要： When the target has large size or the target moves irregularly, traditional inverse synthetic aperture radar (ISAR) imaging method will lead to a poor image quality due to space variate and migration of echo envelop. In this paper, a novel method based on Back Projection (BP) and Particle Swarm Optimization (PSO) is proposed, which can achieve high quality images under the circumstances of irregular motion, large target and low signal to noise ratio (SNR). First, Target motion is modeled as a turntable, then the translational motion and rotational motion are modeled as two polynomials. Entropy of coherent superposition value of part of the imaging scene pixels based on BP algorithm is utilized as the evaluation function to estimate the polynomial coefficients based on an optimization algorithm such as PSO. Once the polynomial coefficients are estimated, a high quality image of the whole scene can be obtained by BP algorithm. The simulation results verify the effectiveness of the proposed method.
关键词： Back Projection (BP),particle swarm optimization (PSO),Inverse synthetic aperture radar (ISAR)
更新于2025-09-10 09:29:36