基于近场测试的相控阵天线自动化校准 与阵面监测方法

相控阵天线装配好之后,由于各组成部件机械加工误差、装配误差、部件老化更换和环境温度改变等因素,各 单元通道的初始幅相产生差异,因此必须对天线的所有系统进行校准。本文针对小型化相控阵平台,通过硬连接将相控 阵天线的波控系统与测试设备相结合,提出一种简便的自动化近场逐点校准方法。同时,本文还提出一种简单的外监测 方法。当相控阵天线工作期间,可对阵面的幅相分布进行监测。可在相控阵天线工作期间,对近场幅相校准数据进行修 正,达到阵面自身校准的目的。经对一个16阵元的相控阵天线进行实验测量可知,该自动化校准与阵面自身校准方法可 以准确、快捷测试出天线阵面的幅相分布。非常适合一维、二维相控阵天线,尤其是小型化相控阵天线的幅相校准与监 测。     

有源相控阵天线的近场校准

为实现对相控阵天线的校准,降低幅相误差和阵元失效对天线性能的影响,提出了一种考虑互耦效应的近场校准方法。在利用近场扫描法完成逐一通道校准的基础上,使用旋转矢量法进行二次校准。在应用旋转矢量法（ REV)时,为使被测信号的变化明显,将大规模相控阵天线分为中间、边缘区域进行分区校准。通过二次校准可判定阵元是否失效,提高相控阵天线的幅相一致性;通过分区校准减小阵元间互耦的影响,缩短校准时间。仿真结果表明：此方法用于大型相控阵的校准具有较高的准确性,可改善校准结果。     

基于耦合线的有源相控阵雷达幅相监测校准方法

介绍了采用校准耦合线对有源相控阵单元进行幅相校准的方法,并就监测支路自身的不一致性给于补偿.最后就发射阵的校准精度及校准时间进行了讨论.     

中场测量相控阵扫描方向图的方法研究

有源相控阵天线的发射和接收天线的性能依赖于阵面口径的幅相分布，有源相控阵的幅相校准工作通常在出厂前通过暗室中的平面近场测量进行，但是某些大型的有源阵面根本无法进暗室进行校准，利用外场测量进行的校准往往无法验证其结果的好坏，该文介绍了一种中场测量相控阵天线扫描方向图的方法，使校准结果能够得到较为客观的评估。     

相控阵发射系统中幅相校准方法研究

提出了一种相控阵发射系统中闭环幅相校准开关阵的方案。从工程实现的角度介绍了校准开关阵的设备组成、特点和性能,论述了相控阵发射系统中幅相校准的原理、分类和实现方式,并详细推导单信道实现幅相检测的算法。该算法利用同一信道幅相误差稳定的特点,建立多组功率测量值的方程,并联立求解出各通道相对基准信道的幅度差和相位差。理论分析和工程实践均验证了该方案的有效性和实用性。     

毫米波阵列近场校准技术

毫米波阵列天线由于其阵元间距小,装配和生产过程带来的误差对通道的初始幅相带来较大的影响,因此必须对其进行校准。介绍了一种基于Phase toggle算法的近场校准方法,该方法不仅能够提高相控阵天线通道间幅相一致性,同时也能减少阵元间互耦的影响。试验结果表明,该校准方法稳定可靠,可有效地实现毫米波阵面的校准,具有广泛的工程适用性。     

一种用PN码校正相控阵天线通道误差的新方法

为了校准相控阵天线通道间幅相误差,实现精确的数字波束形成,给出了一种用伪噪声序列(PN)码作为校准测试信号的在线校准方法(校准和通信可同时进行)。该方法由特定的校准站发送校准测试信号,被天线各阵元接收,并通过存在误差的各通道,在接收端用与发端相同的PN码作为本地信号与接收信号逐通道做相关运算,对各通道的相关峰值做比较可求出校准矢量进而完成校准。仿真结果表明,该方法可以有效校准相控阵天线通道间的幅相误差,校准后的波束方向图接近理想的波束方向图。     

基于海洋回波的高频地波雷达阵列幅相误差校准

针对现有无源校准方法在高频地波雷达中失效的问题,该文提出了一种基于海洋回波的高频地波雷达阵列幅相误差校准算法。该算法利用相控阵中相邻天线对同一海流面元回波之间满足的关系,建立多组幅相误差方程并联立求解。通过对模拟的海洋回波的数据进行处理,分析算法的幅相误差校准值的估计偏差。将此算法应用在实测数据处理中,验证了其有效性及可靠性。     

基于短时FFT的相控阵远场校准方法

相控阵阵面在外场进行幅相测试时,地面折射波引起的多路径效应是一个主要的误差来源.文中介绍了一种在短时FFT基础上、从地面折射波叠加在直射波上的合成波信号中求解直射波信号的方法,并通过软件仿真采用了该方法校准幅相误差后、阵面波束性能的改善情况.     

大型有源相控阵校准的MCM法及其误差分析

文献[1，2]对相控阵天线校准采用互耦测量的方法进行了讨论。本文对此方法进行了推广、并提出了一种用互耦法进行大型有源相控阵校准的新方法──MCM法[3，4]。在整个监测校准过程中，校准测量与各有源通道收／发监测信号幅相大小无关。本文进一步对MCM法的测量误差进行了研究，同时给出了MCM法和近场实测结果，并进行了比较。理论分析和实验结果表明，该方法在工程应用中具有较大的实用价值。     

阵列误差对测向性能的影响及校正方法

深入分析产生阵列误差的主要因素：阵元间互耦、阵元位置误差、通道失配以及它们对超分辨测向的影响，推导出了理论计算公式，并提出利用空间平滑法和改进空间平滑法进行误差校正。计算机仿真实验表明文中方法的正确性和有效性。     

Extended Through-Short-Delay Technique for the Calibration of Vector Network Analyzers With Nonmating Waveguide Ports

The extension of the through-short-delay (TSD) technique to the calibration of two-port vector network analyzers (VNAs) with nonmating waveguide ports is reported. The method retains the well-known high accuracy of the basic TSD technique while it enables to calibrate VNAs using two waveguide ports with different cross sections. Comparisons with the reciprocal-short–open–load technique commonly adopted to calibrate VNAs with nonconnectable ports and with theoretical data are reported. The present method can be adopted as either a one- or a two-tier calibration technique.      

天线方向性误差对DOA估计影响及其校正

天线阵元的方向性误差会导致基于特征值分解的DOA估计算法性能的下降,因此有必要对阵元方向性误差进行校正.首先建立了存在方向性误差情况下DOA估计的数学分析模型,提出利用空间平滑法和改进空间平滑法对方向性误差进行校正.仿真实验表明,方向性误差对DOA估计的影响主要表现在谱峰峰值的降低.空间平滑法和改进空间平滑法均可以有效地对方向性误差进行校正.     

Phased array antenna calibration and pattern prediction usingmutual coupling measurements

A technique which utilized the inherent mutual coupling in an array to both calibrate and predict the radiation patterns of a phased-array antenna is investigated. The only restriction of the technique is that the ability to transmit and receive with pairs of the array elements is required. The theory associated with array mutual coupling and its relationship to both array calibration and array patterns is discussed. The design of a test bed phased-array antenna is covered. The mutual coupling technique (MCT) is used experimentally to calibrate the test array as well as to predict the array radiation patterns. It is shown that the results obtained by MCT are in good agreement with conventional far-field measurements     

Calibration of electromigration reliability of flip-chip packages by electrothermal coupling analysis

Electromigration reliability of solder interconnects is dominated by current density and temperature inside the interconnects. For flip-chip packages, current densities around the regions where the traces connect a solder bump increase significantly due to the differences in feature sizes and electric resistivities between the solder bump and its adjacent traces. This current-crowding effect along with induced Joule heating accelerates electromigration failures. In this paper, the effects of current crowding and Joule heating in a flip-chip package are examined and quantified by three-dimensional electrothermal coupling analysis. We apply a volumetric averaging technique to cope with the current-crowding singularity. The volumetrically averaged current density and the maximum temperature in a solder bump are integrated into Black’s equation to calibrate the experimental electromigration fatigue lives. An erratum to this article is available at .     

The Flat Target Transformation

This paper describes a practical method to calibrate the microwave imaging radiometer with aperture synthesis (MIRAS) in orbit using external targets. Together with the in-orbit validation of the antenna patterns, the method ensures the generation of valid and calibrated visibilities from raw measurements with minimum impact from instrument errors, particularly antenna errors. It has been possible to devise this strategy only after the derivation of the Corbella equation, which correctly describes how MIRAS works. The proposed in-orbit calibration and validation approach is fully based on this equation. In a markedly different way to the point target response method used to calibrate other imaging systems, the technique put forward is essentially based on measuring a ldquoflatrdquo target such as the cold sky near the Galactic poles. This is why it has been called the ldquoflat target transformationrdquo.     

Measurement of impurities in a multi-doped sample of cadmium mercury telluride

A comparative analytical study has been carried out on a specially doped specimen of cadmium mercury telluride using different analytical techniques in order to calibrate solid source mass spectrographic (SSMS) analyses. It has been shown that the conventional technique for standardisation of SSMS that assumes that the ionisation, transmission and collection efficiency of all elements are equal is incorrect with this matrix and can significantly over-estimate the impurity concentration. Enhancement factors for a range of elements have been determined which permit quantitative analyses to be made.     

A novel target designed for the calibration of radars

A technique that can be used to calibrate radar cross section (RCS) levels over a wide dynamic range and to establish overall target signature measurement accuracy is presented. It is based on the development of a specially designed calibration target which is characterized by a linear RCS variation with respect to aspect angle. An inverse scattering technique based on geometrical optics approximation is utilized to define the surface of such a target. Design data describing the surface dimension as a function of the specified maximum and minimum RCS values were developed, and the limitations of the design technique were investigated. An engineering test model covering a 35-dB dynamic range was constructed to verify experimentally the design linearity. priliminary results were excellent.     

Improved polarization measurements using a modified three-antennatechnique

An improved three-antenna measurement of polarization that greatly reduces the uncertainty due to phase measurement errors is described. This technique is used to calibrate polarization standards and probes used in near-field antenna measurements