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地面平面场是用于进行全尺寸或缩比目标模型静态散射特性测量的室外场地。该文从地面平面场的特点入手,分析了在进行目标雷达散射截面(RCS)测量时,目标和定标体因受到测量环境影响而产生的定标误差。在简要阐述地面平面场中的异地定标技术的基础上,综合考虑地面反射和天线方向性两方面的因素,研究了定标体回波强度与放置位置的关系,分析了地面平面场与自由空间的定标之间的差异以及由此所带来的测量误差。最后,通过计算机仿真得到了异地定标误差随定标体测量距离、测量频率以及天线波束宽度的变化规律。通常情况下,定标体放置在靠近目标的位置有利于减小异地定标误差。 相似文献
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A thorough analysis of the uncertainty for dipole antenna calibration is presented. The primary standard of the antenna factor (AF) is obtained by the three-antenna method (TAM), and an ordinary calibration service is performed using the reference-antenna method (RAM). As the AF of the standard antenna is necessary for the RAM, the uncertainty analysis of TAM with the specified antenna setting is presented first, followed by the analysis of RAM. The Guide to the Expression of Uncertainty in Measurement (GUM) shows how to analyze and express the measurement uncertainties. According to the GUM, the uncertainty analysis of the calibration procedure is formulated by expressing AF as a function of other quantities, and every source of uncertainty that affects the result of the measurement is evaluated. An example of the uncertainty budget at 400 MHz is shown, and uncertainties at 24 frequencies in the range of 30 to 1000 MHz for TAM and RAM are summarized. To validate the uncertainty analyses, the differences between the calibrated and calculated AFs are shown to be smaller than the expanded uncertainties with the coverage factor of 2(k=2) 相似文献
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Kahny D. Schmitt K. Wiesbeck W. 《Geoscience and Remote Sensing, IEEE Transactions on》1992,30(5):847-852
A calibration technique for laboratory type polarimetric, bistatic instrumentation radars is presented. It describes the errors induced by the standard radiation transfer approach (I-SRT) in a way similar to that for the monostatic case. A 12-term error correction and absolute polarimetric calibration is performed with two external reference targets. Only the polarimetric bistatic reference of the first target must be theoretically determined. The scattering reference of the second target is determined by a measurement during the calibration process (single reference calibration). The simulation of a third cross-polarization measurement is performed by an antenna rotation and a remeasurement of the second target. Thus all data are gained for the determination of the error terms and measurements of unknown objects can be full polarimetrically calibrated. The procedures are shown for an adapted dihedral corner reflector. Misalignment errors are discussed 相似文献
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本文介绍用天线指向冷空时的天线噪声温度TAN作为定标基准,并以射电源为信标,测量天线剩余噪声温度Tas的基本原理和方法。与用冷、热负载为定标基准测量Tas相比,两者测量结果基本吻合;但该方法具有测量方法简便和测量设备简单等优点。Tas的测量误差约为3%。天线增益测量精度可保持在0.3dB左右。 相似文献
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提出一种新的绝对测量定标方法,并作了误差分析.这种方法基本上具有口面定标法的优良性能;消除了分体定标法的诸多误差项,提高了定标精度.而且在使用中既经济又方便. 相似文献
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三轴天线系统主要用于对低轨卫星的全空域无盲区跟踪。对于斜转台三轴天线系统,已有的方位-俯仰座架的误差模型及标校方法已不适用。依据三轴天线系统的特点,分析研究了三轴天线系统的各项误差,提出了三轴天线系统误差修正的数学模型和标校的具体方法,并结合三轴天线实测数据进行了试验验证。该标校方法已应用于实际工程中,取得了良好的效果。 相似文献
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Wiesbeck W. Kahny D. 《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》1991,79(10):1551-1558
The authors present a scheme for absolute calibration of a polarimetric scattering range. All free-space polarimetric radar cross section (RCS) and antenna measurements are subject to errors like coupling and residual reflections. The modeling of these errors results in a 12-term error correction. The procedure for the error correction with three linear independent calibration targets and an isolation measurement is shown. Based on network analysis, a single reference calibration is introduced. This single reference calibration requires the precise calculation of only one reference target. As single references, spheres or flat plates are used. The references of the other targets are determined by the calibration procedure. The single reference calibration is suitable for all narrow and wideband, complex, polarimetric RCS, and antenna measurements. Measurements are shown for different targets which demonstrate the benefits of the single reference calibration 相似文献
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相控阵天线的指向精度决定着雷达系统对目标的探测精度,甚至会影响跟踪、截获目标的成败。以一种地基相控阵天线为例,详细分析了机电混合扫描天线的指向系统性误差来源:1)热形变导致的单元间距误差,2)空气折射,3)伺服机械转动误差,4)天线内部温度场变化等。从理论上分析了上述因素对天线指向精度的影响,并提出了完整的远场误差校准方法和误差修正流程。试验结果表明,误差来源分析准确,所提出的校准方法可以明显改善天线指向精度,从而提高雷达系统跟踪精度和威力,对于地基乃至移动平台相控阵天线的设计与应用具有重要的参考价值。 相似文献
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论述了用标准场法建立电场探头校准系统的方法,详细地介绍了标准增益天线的研制方案、近场增益计算方法.以及不确定度的评定步骤,重点研究了场地误差不确定度分量的评定过程。所给出的扩展不确定度的可信度较高。 相似文献
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为了实现大尺寸空间异面直线夹角检测系统的现场标定,提出了基于待测对象的现场标定方法。结合一个具体的工程实例介绍了系统的测量方法,针对系统内部机器视觉子模块的测量对象提出了适于现场快速实施的标定策略。分析了影响系统检测精度的各项误差源,给出了系统标定板的设计加工方案。研究了系统的框架设计和标定板布局的合理性。设计了标定环节的数字图像处理流程,并给出了各个步骤的处理结果。实验结果表明,在光照条件为355lx的情况下,采用所提出的标定方法使视觉检测系统的误差均值由0.065123°缩减为0.00219°,补偿效果满足要求,系统对于间隔7m的异面角度的标准测量不确定度为0.114°。 相似文献
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Matsumoto Y. Umeda T. Nishikata A. Fujii K. Yamanaka Y. Sugiura A. 《Electromagnetic Compatibility, IEEE Transactions on》2003,45(4):656-660
Theoretical and experimental investigations are carried out on the establishment of a quasi-free-space environment for electromagnetic interference antenna calibration using ferrite-tile absorbers at the test site. Numerical techniques are developed to evaluate the accuracy of the free-space antenna factor obtained on the absorbers when the ferrite-tile material constants are known. In addition, the antenna impedance measurement on a tuned dipole antenna is proposed for evaluating the calibration error caused by the unwanted ground reflection. Experiments confirm the validity of the numerical techniques and demonstrate that commercially available ferrite tiles can drastically reduce ground reflection even in a lower very-high-frequency (VHF) range. It is concluded that the standard antenna method can yield free-space values of the antenna factor for the entire VHF region with an error of less than 0.3 dB, if ferrite tiles are placed on a metal ground plane greater than 8.7/spl times/8.7 m/sup 2/ and if the antenna under calibration is positioned at a height of about 3 m. 相似文献
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微波辐射计的功率非线性对标定天线温度的影响 总被引:1,自引:0,他引:1
微波辐射计通过两点定标反演天线温度依赖的是辐射计的输入功率与输出电压的线性关系。通过分析平方律检波器的输入功率与输出电压的关系,导出非线性系数与由口面定标法反演的天线温度误差的关系式。定量说明了功率非线性度引入误差的大小.通过计算分析得出两种定标系统(地面遥感和星载遥感)对功率非线性度的要求。 相似文献
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首先推广了现有极化定标模型。在此基础上,评估了极化通道幅相不平衡、天线串扰、法拉第旋转、指向误差角、干扰和系统环境噪声对点目标全极化散射测量的影响,并考虑科学研究和应用需求对上述参数的约束条件,从而得到对极化合成孔径雷达系统设计和极化定标有参考价值的结论。 相似文献
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Airborne Along-Track Interferometric Synthetic Aperture Radar (ATI-SAR) baseline error is a main error resource affecting the precision of velocity measurement of moving objects and therefore should be calibrated externally. The Jet Propulsion Laboratory (JPL) has proposed a calibration scheme for tasks of PacRim98 and PacRim2000 based on several static objects on the ground. In this paper, the influence of phase center uncertainty on baseline determination by using PacRim method proposed by JPL is analyzed. According to the analysis, the phase center uncertainty can cause a constant part of error to the result of baseline calibration. In order to deal with this problem, an improved calibration method on the basis of sensitivity equations and some ground moving targets, whose velocities are already known, is proposed in this paper. The simulation results show that our proposed calibration method has improved the accuracy of baseline calibration and has obviously prohibited the effect of antennas?? phase center uncertainty. 相似文献