天线时域平面近场测试的误差分析

天线时域近场测试技术对误差体系研究的缺失,导致测试结果的不确定度分析一直无法完成.为解决这一问题,以天线时域平面近场测试为例,对时域近场测试的误差进行研究,给出时域测试区别于频域测试技术的四个误差项:探头调制误差、信号源稳定度误差、时间采样间隔误差、时间采样长度误差.在给出误差项后,对误差的产生机理进行了讨论,通过仿真和实测给出了误差对测试结果的影响.     

天线时域平面近场测试实验系统的研究

天线时域近场测试技术是一种新兴、高效的天线测试技术,能够快速精确地测量出天线的时域场和宽带特性。目前我们已成功组建了国内第一套天线时域平面近场测试实验系统,并对L、S、C、X四个波段的标准天线方向图进行了验证测试,把测试结果跟频域近、远场测试系统上测得的结果进行比较,证明时域近场测试理论的正确性和测试系统的实用性。本文对这套系统的组成结构和天线的测试结果进行说明分析。     

天线时域近场测量实验系统研究

总结了天线时域近场测量技术研究中进行系统实验验证在个阶段的进展情况,提出了组建天线时域近场测试验证系统的基本框架,总结了验证实验的基本过程和思路,提出了一种利用离散傅立叶反变换（IDF）技术完成天线的时域近场测量的方法,本文给出了各个实验阶段的测试结果,据此得出了对于天线的时域近场测量技术肯定的结论。     

时域近场测试中的探头误差分析与修正

探头误差分析和修正是时域近场测量中的关键技术.本文详细推导了探头自身接收特性误差函数在修正过程中的坐标变换关系,提出用 '时间窗' 技术隔离掉探头和待测天线之间的多重反射波,并导出'时间窗’的选取原则,数值结果证明了理论和方法的有效性.     

天线时域平面近场测量系统的研究

时域近场测量作为一种新发展起来的天线测量技术,具有和通常的频域测量不同的独特优势,它能得到天线的时域特性和宽带特性.首先介绍了时域平面近场测量系统的构成,为了能对雷达进行测量,系统采用了使用矢量信号源模拟产生复杂雷达信号的方案,并对标准增益喇叭进行了验证测试,把测试结果和理论仿真、频域近场测试结果进行了比对,证实了时域...     

天线时域近场测量技术与实验系统

天线时域近场测试技术是一种新兴、高效的天线测试技术,能够快速精确地测量出天线的时域场和宽带特性。介绍了成功组建的国内第一套天线时域平面近场测试系统简单情况,给出了L、S、C、X四个波段的标准天线方向图验证测试结果,把测试结果跟频域近、远场测试系统上测得的结果进行了比较,证明测试理论的正确性和测试系统的实用性。     

时域平面近场散射测量研究

时域平面近场散射测量是一种在近场区域进行散射测量的技术,可以有效地进行宽带的散射测量,具有超宽带测试、可以获得时域散射场、空间利用率高等特点,针对时域平面近场散射测量技术体系,在时域近场测量的理论基础上,提出了系统组建方案,论证了系统的可行性,开展了针对典型目标的验证测试,并对测量结果进行了初步的误差分析.证明了时域平面近场散射测量的有效性.     

基于Labview的时域近场天线测试技术的直接时域算法

讨论了时域近场天线测试的直接时域算法理论,阐明了利用Labview编程实现基于直接时域算法的方案和方法,并以高斯点源天线为例验证了其准确性,得出了相关的结论.     

天线时域近场测量中的时基及幅度修正技术

 在天线时域近场测量中由于脉冲信号源的时基抖动和幅度变化所带来的误差是测量中最主要的误差,其中尤以时基误差最为严重,它使得方向图畸变到了无法容忍的程度.本文即针对此问题提出了天线时域近场测量中的时基及幅度修正技术.该技术在测量通道之外增加了一个参考通道,通过检测参考通道信号提取出脉冲信号源的时基及幅度变化,进而以此修正测量通道的信号.大量的实际测量表明该技术稳定可靠.通过对比试验发现,使用该技术的时域近场测量结果的精度达到甚至优于频域近场测量结果的精度.     

一种减小相控阵天线球面近场测量截断误差的方法

在相控阵天线球面近场测量中,有限扫描面和相控阵天线波束扫描将会引起较大的截断误差.为了解决这一问题,提出利用基于遗传算法参数优化的余弦窗函数对近场数据进行加权处理的方法来有效减小截断误差.以半波振子组成的矩形平面阵作为待测天线,对相控阵天线球面近场测量进行了计算机模拟.模拟结果表明,通过对近场数据进行加余弦窗的处理并用遗传算法对参数进行优化能够大大减小相控阵天线波束扫描时的有限扫描面截断误差,从而证实了文中所提出方法的正确性和有效性.     

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。     

天线近场测量系统的控制设计综述

近年来 ,近场测量已成为高性能天线研制中非常重要的技术手段 ,其中高精度是天线近场系统中的关键指标 ,这使得近场控制技术显得尤为重要。早期的近场控制借助于成熟的经典控制技术 ,保证系统的可靠运行。而近期的近场系统多采用具有精确、简捷、快速的新型步进控制技术 ,对提高控制性能、简化控制设计、降低系统成本 ,起到了显著作用。综述了天线近场测量控制系统的设计 ,给出了控制方式、误差补偿及系统设备配置方面的设计建议 ,对从事近场系统控制人员具有一定的指导和参考意义。     

基于傅立叶变换频移特性的平面近场测试方法

为了满足快速和无相测试现场天线的需求,文中提出了一种基于傅立叶变换频移特性的平面近场测 试方法。该方法采用多探头技术,利用各个通道的移相,达到天线角域的移动,实现了任意指向角信号的采集,具有 测试快速、使用便捷的特点,特别适用于天线的大规模生产测试和现场测试等。对一个标准喇叭天线进行了平面近 场扫描测量,对比了用传统近场数据处理插值方式得到的和用频移性质得到的天线远场方向图(E 面)。实验显示, 该方法具有与传统近场测试方法相同的效果,能有效地测试天线方向图。     

Formulation of probe-corrected planar near-field scanning in thetime domain

Probe-corrected planar near-field formulas in the time domain are derived for both acoustic and electromagnetic fields, so that a single set of near-field measurements in the time domain yields the fields of the test antenna directly in the time domain. The time-domain probe-corrected formulas are first derived by taking the inverse Fourier transform-of the corresponding frequency-domain formulas, and then by using a time-domain expansion for the fields of the test antenna and a time-domain receiving characteristic of the probe. Because these general formulas, which involve a double integral over the scan plane and an infinite time-convolution integral, are rather complicated, we consider a special probe whose output due to an incoming time domain plane wave is proportional to the time derivative of the field of that plane wave. For this special “D-dot probe”, the probe-corrected formulas simplify to give the time-domain far-held pattern as a double spatial integral of the time-domain output of the probe over the scan plane multiplied by the angular dependence of the inverse receiving characteristic of the probe. Time-domain reciprocity relations are derived for reciprocal probes, and their time-domain receiving characteristics are related to their far fields. Finally, a time-domain sampling theorem is derived and a numerical example illustrates the use of the time-domain probe-corrected formulas     

Far-field patterns of spaceborne antennas from plane-polar near-field measurements

Certain unique features of a recently constructed plane-polar near-field measurement facility for determining the far-field patterns of large and fragile spaceborne antennas are described. In this facility, the horizontally positioned antenna rotates about its axis while the measuring probe is advanced incrementally in a fixed radial direction. The near-field measured data is then processed using a Jacobi-Bessel expansion to obtain the antenna far fields. A summary of the measurement and computational steps is given. Comparisons between the outdoor far-field measurements and the constructed far-field patterns from the near-field measured data are provided for different antenna sizes and frequencies. Application of the substitution method for the absolute gain measurement is discussed. In particular, results are shown for the 4.8-m mesh-deployable high-gain antenna of the Galileo spacecraft which has the mission of orbiting Jupiter in 1988.     

Sampling in plane-polar coordinates

A number of details are clarified regarding the sampling-reconstruction theorem for near-field scanning in plane-polar coordinates. The rigorous sampling-reconstruction theorem is applied to the near-field measurement of a circular aperture test antenna offset from the plane-polar axis of rotation, so that a large number of angular modes are necessary to represent the fields of the test antenna. An algorithm is described for computing accurately and rapidly the required zeros of Bessel functions of arbitrary integer order     

Test zone field compensation

Test zone field (TZF) compensation increases antenna pattern measurement accuracy by compensating for extraneous fields created by reflection and scattering of the range antenna field from fixed objects in the range and by leakage of the range RF system from a fixed location in the range. TZF compensation can be used on fixed line-of-sight (static) far-field, compact, and near-field ranges. Other compensation techniques are seldom used in practical measurement situations because they are limited in the amount of compensation they provide. These techniques do not adequately model the type of extraneous field present in the range or require increased measurement time and equipment necessary to implement the technique. TZF compensation overcomes these limits as follows. The TZF is measured over a spherical surface encompassing the test zone using a low gain probe. The measured TZF is used antenna pattern measurements to compensate for extraneous fields. TZF compensation theory is presented and demonstrated using measured data