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1.
The SIR-C/X-SAR Synthetic Aperture Radar system 总被引:14,自引:0,他引:14
Jordan R.L. Huneycutt B.L. Werner M. 《Geoscience and Remote Sensing, IEEE Transactions on》1995,33(4):829-839
The Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) was a joint United States/German/Italian space agency imaging radar system successfully flown aboard the shuttle Endeavor in April 1994 and again in September/October 1994. The multifaceted SIR-C/X-SAR represents a major technological step forward in radar remote sensing and is the first spaceborne multifrequency, polarimetric SAR. The United States developed SIR-C operated at L- and C-band, each with quad polarization. The SIR-C antenna was an active phased array, with the capability for electronic beam steering and multiple swath width illumination. The German/Italian X-SAR operated at X-band with a single polarization using a slotted waveguide antenna, mechanically steerable in elevation. SIR-C and X-SAR were designed to operate synchronously, collecting data over common sites synchronously. A total of 143 hours (93 terabits) of SAR data were recorded on tape 相似文献
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SIR-C data quality and calibration results 总被引:5,自引:0,他引:5
Freeman A. Alves M. Chapman B. Cruz J. Kim Y. Shaffer S. Sun J. Turner E. Sarabandi K. 《Geoscience and Remote Sensing, IEEE Transactions on》1995,33(4):848-857
The SIR-C/X-SAR imaging radar took its first flight on the Space Shuttle Endeavour in April 1994 and flew for a second time in October 1994. This multifrequency radar has fully polarimetric capability at L- and C-band, and a single polarization at X-band (X-SAR). The Endeavour missions were designated the Space Radar Laboratory-1 (SRL-1) and -2 (SRL-2). Calibration of polarimetric L- and C-band data for all the different modes SIR-C offers is an especially complicated problem. The solution involves extensive analysis of pre-flight test data to come up with a model of the system, analysis of in-flight test data to determine the antenna pattern and gains of the system during operation, and analysis of data from over fourteen calibration sites distributed around the SIR-C/X-SAR orbit track. The SRL missions were the first time a multifrequency polarimetric imaging radar employing a phased array antenna has been flown in space. Calibration of SIR-C data products involved some unique technical problems given the complexity of the radar system. In this paper, the approach adopted for calibration of SIR-C data is described and the calibration performance of the data products is presented 相似文献
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Seifert P. Lentz H. Zink M. Heel F. 《Geoscience and Remote Sensing, IEEE Transactions on》1992,30(6):1131-1136
An approach is presented for determining the inflight antenna pattern in the cross-track direction for air- and spaceborne synthetic aperture radar (SAR) systems. In the 1991 Oberpfaffenhofen DC-8/E-SAR calibration campaign, ground-based measurement, equipment comprising 18 precision calibration receivers and nine polarimetric active radar calibrators, all operating in C -band, were tested. These instruments are capable of handling various pulse lengths and repetition frequencies, and they have a very high dynamic range. Together with precise internal clocks, these instruments are suitable for recording the actual radar transmit pulse shape for the later evaluation of the desired inflight antenna pattern. Lining up these devices in the cross-track direction, each receiver yields an azimuth cut of the three-dimensional antenna pattern. The elevation pattern was then obtained by time correlation of these azimuth cuts. Further results concerning pulse shapes, squint angles, and H-V pattern misalignment are presented 相似文献
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介绍了一种双波束相控阵天线,阐述了其工作原理、设计方法及实测结果。该天线阵工作于P波段,用于雷达干扰发射系统,发射波束为方位同时双波束,并且每个波束均可独立电扫描,实现了同时对多目标、多方位的雷达干扰。 相似文献
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介绍了一种宽频带双极化低副瓣天线的设计、加工方法和测试结果。采用馈源偏置的方法来减小副瓣,采用波纹喇叭实现天线双极化的要求,并且采用双椭圆切割抛物面来增加天线的效率和减小方位主波束宽度。天线的理论分析与实验结果吻合较好,优于所需的技术指标要求。 相似文献
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邱德厚 《太赫兹科学与电子信息学报》2019,17(5):845-849
提出一种实波束扫描雷达前视成像回波建模方法。使用实波束扫描实现雷达平台正前视区域二维高分辨成像。根据雷达波束掠过成像扇区的时间先后关系,将成像扇区方位向回波数据表征为天线主瓣波束采样序列与目标反射率分布函数沿成像扇区方位向采样序列之间卷积的形式。最后,通过仿真数据验证了本建模方法的有效性。 相似文献
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This paper describes an X-band 4×1 aperture-coupled series-fed electronically steerable microstrip leaky-wave antenna (LWA) array design, which has dual-beam radiation pattern and two-dimensional (2-D) beam-scanning capability. The LWA array is operated in the first higher order mode and excited by center-fed aperture coupled for dual-beam operation. The varactor-tuned phase shifters are placed between the antenna elements. The measured half-power beamwidth of the H-plane and quasi-E-plane radiation patterns are less than 30°. By tuning the reverse dc bias of the varactor diodes, the main beam can be scanned in azimuth plane from -13° to +13° off broadside. In the elevation plane, the beam-scanning angle is close to 20° as the operating frequency tuned from 11.58-12.5 GHz. Taking into account each phase-shifter insertion loss and phase progression, the measured results compared closely with the theoretical prediction. The proposed antenna array is suitable for wireless communication and collision warning radar systems 相似文献
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海面反射对一维相控阵天线影响的研究 总被引:1,自引:0,他引:1
海面反射引起的多径干涉效应,会造成宽波束雷达天线的俯仰波束分裂,导致雷达观测的盲区和目标跟踪丢失.文中从天线和电波传播的观点出发,分析了海面上单脉冲二次雷达询问天线的三维方向图特性,阐述了天线波束干涉的原理.详细分析海基一维相控阵雷达天线在姿态倾斜后的方位面和俯仰面干涉方向图,讨论了由于方向图变化引起的系统测角偏差,总结了降低多径影响的方法. 相似文献
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A single-frequency multibeam synthetic aperture radar concept for large swath imaging desired for global oceanography is evaluated. Each beam illuminates a separate range and azimuth interval, and images for different beams may be separated on the basis of the Doppler spectrum of the beams or their spatial azimuth separation in the image plane of the radar processor. The azimuth resolution of the radar system is selected so that the Doppler spectrum of each beam does not interfere with the Doppler foldover due to the finite pulse repetition frequency of the radar system. 相似文献
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针对宽波束天线在车载雷达中的应用,突破角雷达方位面3 dB波束宽度的限制,实现微带阵列天线在水平面的宽波束覆盖,设计了一款1×10串馈微带双层结构天线。线阵单元采用道尔夫-切比雪夫(Dolf-Chebyshev)综合法电流分布来达到降低天线俯仰面副瓣的效果,在串馈阵列上方加载寄生贴片和介质基板拓展天线方位面的3 dB波束宽度。分析了双层天线展宽波束的原理,加工并实测了双层宽波束天线,其方位面的3 dB波束宽度为134.6°,增益达到10.6 dB,副瓣电平为-19.8 dB,可以满足车载角雷达天线需求。 相似文献
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Brautigam B. Gonzalez J. H. Schwerdt M. Bachmann M. 《Geoscience and Remote Sensing, IEEE Transactions on》2010,48(2):702-715
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针对相控阵单脉冲雷达体制测角的情况,本文提出了一种降维双和/三差通道自适应同时抑制主、副瓣干扰的算法.该算法利用权值逼近的方法,在非均匀子阵上形成静态和、俯仰差、方位差、双差波束以及指向副瓣干扰方向的和波束,差波束、指向副瓣干扰的和波束作为静态和波束的辅助波束,双差波束作为差波束的辅助波束,根据维纳滤波原理通过对辅助波束的优化加权对消掉和波束中的主副瓣干扰信号及差波束中的主瓣干扰信号,设计出一种新的干扰抑制和测角跟踪算法.所提算法结构简单、测角精度高、能同时抑制主副瓣干扰且鉴角斜率无需修正.仿真实验和性能分析证明了所提算法的有效性和正确性. 相似文献
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距离模糊和方位模糊会严重影响星载合成孔径雷达(Synthetic Aperture Radar,SAR)的成像质量。现有的利用天线波束赋形来抑制模糊的方法在雷达正侧视成像时取得了优异的效果,但并不适用于雷达斜视的情况。针对这一问题,提出了一种基于平面阵列天线波束赋形的星载SAR二维模糊(距离和方位模糊)抑制方法。使用距离-方位模糊综合的模糊比(Ambiguity to Signal Ratio,ASR)指标来替代距离模糊比及方位模糊比,结合对不同斜视情形下天线波束变化的分析,充分考虑包含镜像模糊区在内的所有模糊区,建立了模糊比-天线权重优化模型。以模糊能量为目标函数、天线方向图掩模作为约束确立二次锥(Quadratic Cone Programming,QCP)优化问题,求解得到阵元幅度相位分布。仿真结果表明,所提方法可以通过调节模糊区对应的旁瓣幅值,灵活地抑制SAR斜视成像的距离和方位模糊,进而提高星载SAR的成像质量。 相似文献
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X-SAR radiometric calibration and data quality 总被引:5,自引:0,他引:5
In April and October, 1994 the X-SAR was flown as part of the SIR-C/X-SAR space radar laboratory missions (SRL-1/2) on the Space Shuttle. Amongst other activities DLR is responsible for the calibration of all X-SAR data products and is running the German Processing and Archiving Facility (D-PAF). Calibration activities included three major parts. Before the first mission, the authors performed a detailed analysis of the overall system to localize the main error sources and developed algorithms and procedures to correct these errors. During the missions they concentrated their efforts on calibration campaigns at the Oberpfaffenhofen super test site. Post mission activities included the determination of the antenna pattern and the absolute calibration factor as well as detailed performance analyses. This paper describes the overall approach to radiometrically calibrate the X-SAR and provides information on system performance and data quality to users in the different application fields 相似文献
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Q. Md. Alfred T. Chakravarty G. Singh S. K. Sanyal 《Journal of Infrared, Millimeter and Terahertz Waves》2007,28(10):881-887
In radar, planar phased array antenna plays vital role in electronic scanning in the azimuth and elevation direction to the horizon. In most operations using planar phased array both the coordinates of azimuth and elevation, are steered electronically. In this paper a conceptual schematic of a phased array antenna with programmable time delay units has been presented. It is shown that by suitably exploiting the time delay matrix one can have electronic beam rotation around the target axis as required in conical scan. Thus both the elevation and azimuth motors in conical scan system are replaced by electronic scanning. Heuristically, we have selected eight consecutive points for beam rotation in a polygon shape and can also be extended almost circular shape by increasing number of array elements and phase shifter (delays) in the delay matrix. The array requires dual control of phase gradient and individual phase values. The whole array is controlled by micro-controller. This presents exciting possibilities in radar operation. 相似文献
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分析了米波波段背靠背双天线雷达实测原始点迹数据,列出了不同情况下目标点迹参数的分布,对比了中心法、峰值法、幅度加权法三种方法获得的目标方位数据的分布与特性。比较表明:对米波雷达而言,采用幅度加权方法获取目标方位,其精度较高。 相似文献
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低频UWB SAR天线方向图校准算法 总被引:2,自引:0,他引:2
低频UWBSAR具有较大的方位向处理角,因此天线方向图沿方位向的变化不能忽略。本文给出SAR系统的时域处理模型,利用该模型分析天线方向图对系统性能的影响,然后给出天线方向图的校准算法,以及该算法的性能分析。最后通过计算机仿真,验证该算法的有效性,得到的仿真结果和理论分析相吻合。 相似文献