平面近场测量的“诊断”技术

对近场测量的“诊断”技术技术进行了理论和实验研究，采用反演技术重构被测天线的口径分布，实现对被测天线的“诊断”，找出阵列天线失效单元的位置。     

窗函数在相控阵天线平面近场测量中的应用

有限扫描面截断是影响天线平面近场测量精度的主要误差源之一，尤其是对于波束扫描的相控阵天线的平面近场测量更是如此。为了减小相控阵天线平面近场测量中的有限扫描面截断误差，介绍了余弦窗函数并将其应用到相控阵天线平面近场测量中。计算机模拟结果表明，通过对近场进行加余弦窗的数据处理能够有效地减小有限扫描面截断误差。提出了对近场数据进行加余弦窗处理的适用条件。     

大型星载网状天线型面检测技术与工程实践

将工业数字摄影测量技术应用于某17m口径网状天线的型面精度检测中:采用回光材料制作人工标志,利用编码标志来完成摄站的自动定向和同名点匹配,经光束法平差解算点的坐标,用CAD面型转换法来计算型面偏差。通过工程实践成功验证了数字摄影测量方法具有测量精度高、测量速度快和动态性能好等优点,特别适合大型网状天线的型面检测。     

大型相控阵雷达天线阵面结构精度分析及控制

天线阵面结构精度是雷达结构设计中需要控制的关键指标之一。文中首先分析了结构精度对阵列天线极化特性的影响,通过理论公式可以推导出合理的精度指标要求,随后以某大型天线阵面为研究对象,分析了影响阵面结构精度的各个因素,并对各因素进行了误差分配以及控制方案制定。在天线装配中将摄影测量法应用于天线平面度的检测,基于测量结果的调整后平面度可控制在0.4mm内,其安装精度满足平面度指标要求。该方法为同类天线阵面平面度分析及控制提供了有益的参考和借鉴。     

副面修正卡塞格伦天线设计中的几个问题

本文根据几何光学理论,介绍了副面修正双反射面天线组合馈源相位中心的计算方法.并利用并矢反射系数,导出了包括差波束在内的副面散射场及天线口径分布,因而解决了副面修正天线性能参数的计算问题.     

极低副瓣天线远场测量的新方法

测试极低副瓣天线时，要求测量距离远远大于２Ｌ＾２／λ，其中Ｌ为天线口径尺度，λ为工作波长。为了解决现有远场测试场地测量极低副瓣天线所遇到的测试距离不够的问题，本文提出了一种远场测量修正方法。对在费涅耳区测量的天线波瓣图进行修正，可以获得被测天线的远场波瓣图。对极低副瓣线阵天线的计算机模拟计算表明，该方法是有效的，可以获得满意的校正效果。     

点聚焦透镜天线分辨率的分析与测量

采用波动理论方法分析了平面电磁波经点聚焦透镜天线会聚后焦斑大小和横向空间分辨率，得出了此类天线在会聚点的天线特性与平面口径天线在无穷远处的天线特性的关系，提出了透镜天线分辨率的一种测量方法。通过实测，测量结果和理论较为吻合。     

随机误差对超低副瓣天线平面近场测量的影响

导出了平面近场测量中近场幅相随机误差所引起的误差谱的解析表达式。利用计算机模拟和统计平均的方法研究了近场幅相随机误差对超低副瓣天线平面近场测量结果的影响 ,并给出不同口径尺寸的超低副瓣天线的平面近场测量 ,为保证- 5 5 d B副瓣± 5 d B的测试精度 ,所能允许的近场幅相随机误差的最大起伏度     

单面修正卡氏天线的一种CAD方法

电小尺寸卡塞格伦天线，仅修正副面（使主面口径场幅度均匀或略有坡变）即可提高天线效率。对给定电小尺寸口径抛物面天线，本文详述了一种副面修正计算的方法，据此理论，我们成功地进行了C波为6m天线的修正设计，测试表明，只要将副面／喇叭组合馈源，从计算等效相心处沿轴向向外调速约20mm，天线增益即达最佳（口径相程差最小）。     

平面阵列天线面精度测量值的分析计算方法

本文介绍的是平面阵列天线面精度测量值的分析计算方法。由于天线面精度对天线副瓣，特别是低副瓣天线的副瓣影响甚大。近年来越发为设计人员所重视，在完成天线安装后得到可靠的阵面面精度测量数据以便于设计人员进行评估和分析，用本文提出的数据处理方法进行测量值分析计算不失为一种简单易行的办法。     

平面波谱恢复算法在平面近场测量中的应用

介绍用于天线平面近场测量的一种近远场变换新算法。该法利用被测天线的平面波谱和口径场幅相分布之间的关系,以及天线口面的约束条件,用G-P迭代算法从平面波谱的置信谱域部分恢复出置信谱域外的平面波谱。这种方法减小了较小截断角下有限扫描面对测量精度的影响,并提高了天线近场测量的效率。     

“三元组近场”新型幅度控制精确算法

在电磁辐射和散射测量时，为使目标处于平面波照射区，被测目标和天线的距离应满足远场条件。但是在一些电子战设备进行暗室内性能测试时，根据这些设备的工作波长和天线口径，则需要建造很大的微波暗室，事实是在很多情况下是不现实的。为此，详细推导了一种“三元组近场”条件下的幅度控制精确算法，该算法能将辐射式仿真远场测试距离降低约1倍，实现近场效应修正，可以广泛应用于工程实践。     

Near-field diagnostics of small printed antennas using theequivalent magnetic current approach

A near-field to far-field transformation based on the antenna representation by equivalent magnetic current (EMC) sources has been proposed and validated experimentally on large high-directivity antenna arrays. In this paper, the use of EMC is extended to the diagnostics of low-directivity printed antennas. The limitation of the near-field to far-field transformation applied to EMC models of low-directivity antennas, caused by the finite dimensions of the antenna ground plane, is demonstrated. A method to partially overcome this limitation by including the contribution of diffracted rays is implemented, and its effectiveness is demonstrated with antenna prototypes. It is shown that the agreement between the far-field patterns measured in an anechoic chamber and the patterns computed from the EMC model obtained from the near-field measurements is significantly improved upon, within a sector of ±90° with respect to the antenna boresight in the E plane. The influence of the near-field sampling density and topology of the EMC model on the accuracy of the predicted far-field pattern is examined     

Analysis of phase-focused near-field testing for multiphase-centeradaptive radar systems

Airborne or spaceborne radar systems often require tests before deployment to verify how well the system detects targets and suppresses clutter and jammer signals. The radar antenna diameter can be large and thus the conventional far-field test distance is impractical to implement. The theory and simulations of phase-focused near-field testing for adaptive phased array antennas is discussed. With near-field source deployment, standard phased-array near-field phase focusing provides far-field adaptive nulling equivalent performance at a range distance of one aperture diameter from the adaptive antenna under test. Both main beam clutter sources and sidelobe jammer sources are addressed. The phased array antenna elements analyzed are one-half wavelength dipoles over the ground plane. Bandwidth, polarization, array mutual coupling, and finite array edge effects are taken into account. Numerical simulations of an adaptive antenna that has multiple displaced phase centers indicate that near-field and far-field testing can be equivalent     

平面近场天线多任务测试系统工程设计

提出了一种平面近场天线多任务测试系统的工程设计方法,该方法通过增加多功能天线测试控制器和远控微波开关对传统平面近场测试系统进行升级,使其具备对平面相控阵雷达天线多频点、多波位、多通道一次最多可测试35个天线方向图的测试能力。对新引入的幅相误差及扫描面截断误差进行了计算分析。大型相控阵天线的实测结果表明,在提高测试效率的同时,其测试精度亦能满足测试要求。     

Near-field analysis by the plane-wave spectrum approach

Historically, most near-field analyses have relied upon aperture-integration techniques. The purpose of this paper is to point out the advantage of the plane-wave spectrum (PWS) approach for analysis of antenna near fields. The advantage of the PWS approach over aperture-integration techniques is quite substantial throughout the entire near-field region for circular apertures. Furthermore, the advantage increases in proportion to closeness to the aperture. The PWS approach also appears to offer advantage for noncircular apertures, e.g., rectangular, at least for large aperture sizes.     

车载天线整车测试系统集成与实现

针对自动驾驶、车联网等新技术场景下汽车天线整车性能测试的新需求,借鉴近年来近场测量技术的研究成果,设计采用半球面近场与平面近场相结合的方式,集成了一套汽车天线整车测试系统。系统基于8 m 直径的方位转台实现了中小型汽车的车载天线测试定位,基于12 m 直径的弧形多探头采样架实现了400 MHz~6 GHz工作频段内的车载通信天线半球面近场测试,基于扫描行程为宽3 m 高2.5 m 的单探头采样架实现了6~80 GHz工作频段内的车载雷达天线平面近场测试。在校准场内,以定标喇叭天线作为系统性能验证天线进行远近场测试结果比对。测试结果表明,本系统具备宽频带、多功能、高精度、高效率等特点,是国内测量车载天线的优良实验平台。     

基于最小二乘法的平面波综合

将最小二乘法引入近场天线测量中,提出了一种新的平面波综合方法。以半波对称振子组成的矩形平面阵作为平面波综合的理论模型,用这一新方法寻求阵列单元的最佳幅相分布,以使所综合出的准平面波质量最好。计算结果表明在待测区域大小一定的条件下,利用本文方法可以实现较传统方法更小的探头阵列要求。良好的仿真结果证实了该方法在天线测量及散射测量应用中的有效性。     

Reduction of Truncation Errors in Planar Near-Field Aperture Antenna Measurements Using the Gerchberg-Papoulis Algorithm

A simple and effective procedure for the reduction of truncation errors in planar near-field measurements of aperture antennas is presented. The procedure relies on the consideration that, due to the scan plane truncation, the calculated plane wave spectrum of the field radiated by the antenna is reliable only within a certain portion of the visible region. Accordingly, the truncation error is reduced by extrapolating the remaining portion of the visible region by the Gerchberg-Papoulis iterative algorithm, exploiting a condition of spatial concentration of the fields on the antenna aperture plane. The proposed procedure is simple and computationally efficient; it does not require any modification of the measurement procedure and it allows for the usual probe correction. Far-field patterns reconstructed from both simulated and measured truncated near-field data demonstrate its effectiveness and stability against measurement inaccuracies.      

Near-field probe used as a diagnostic tool to locate defectiveelements in an array antenna

Results of an experimental study are presented in which the near-field probe was used as a diagnostic tool to locate the defective elements in a planar array. The near-field data were processed not only to obtain the far-field patterns of the array under the test, but also to reconstruct the aperture field for diagnostic purposes. The backward transform enables the near-field probe to identify accurately aperture faults at a distance, free of interactions and couplings with the array elements. In practice, to recover the aperture field properly from the near-field distribution, the evanescent components in the computed far-field spectrum must be excluded from the inverse process with fast-Fourier-transform (FFT) techniques. For low-gain array antennas, a correction on the far-field spectrum is required to remove the contribution of the probe and the element factor before the inverse transform, strongly enhancing the resolution