数字阵雷达天线波瓣图测试方法与试验验证

针对固定式相控阵雷达在中场法或远场法中不能实时得到天线波瓣图的问题,提出了采用扫描波瓣图替代天线波瓣图进行天线测试的方法。从理论上分别推导了和波束与差波束扫描波瓣图和天线波瓣图的解析式,研究了单元波瓣图对扫描波瓣图和天线波瓣图的影响,指出了在单元波瓣主瓣范围内扫描波瓣图和天线波瓣图近似等价。仿真和试验结果 均表明:扫描波瓣图和天线波瓣图在各项性能指标上都是等价的,可用于指导雷达总体依据扫描波瓣图对天线进行验收。     

数字式雷达天线方向图模拟器

数字式天线方向图发生器(或叫雷达天线模拟器)用于产生一个电信号,来模拟任一所希望的天线方向图,此方向图是预先编好程序存在发生器里的。利用按照可用信息数据进行预调的只读存贮器,是为了当存贮单元依次进行寻址时读出所希望的雷达天线方向图。在本发明介绍的具体设备中,只读存贮器按照天线波束方向图上的角位移顺次进行寻址。在另一个具体设备中,介绍了可以对波束宽度、停滞时间和波瓣速率进行调整的自由振荡天线方向图发生器。两个系统把只读存贮器产生的数字式天线方向图转换成适当的模拟输出信号。     

天线波瓣图检测系统

天线方向图、增益、波瓣宽度是表征天线性能的主要参数，本文首先介绍了天线波瓣图检测系统的基本原理，接着给出了系统性能以及主要技术指标，并结合实际设计过程中的难点讲述了解决问题的主要手段，利用本软件可以大大提高天线波瓣检测的效率，缩短开发时间，具有较高的实用价值。     

斜极化和圆极化天线波瓣图免失真测试研究

文章通过详细的理论分析,给出了待测天线免失真波瓣图的正确测试方法和修正手段,并指出：在天线波瓣图远场测试中,通常所说的＂检验天线与待测天线极化方向须相同＂这一规定不准确;由此而提出新的观点：水平极化的待测天线做接收,斜极化、圆极化待测天线做接收或发射,远场测试得到的波瓣图都将受到并非待测天线自身属性的极化匹配因子的调制而失真。     

一种新颖实用的探空仪接收天线

文章介绍了一种新颖小巧的炮兵气象雷达探空仪接收天线。此天线寄生在雷达天线上，波束最大指向与雷达天线的电轴完全重合，且覆盖雷达天线主波束，该天线具有半功率点波瓣宽度窄，副瓣性能好，频率宽度大于５％等特点。     

高机动三坐标雷达比幅测高误差分析及修正

讨论了比幅测高的基本原理,分析了影响比幅测高精度的各种因素。定量计算了由这些因素引起的误差量。并提出了一种简单易行的修正方法,即根据一次雷达的测高值和二次雷达的测高值计算出天线波束指向的调整量,对天线阵面波束指向进行微调,从而提高了测高精度。由于对天线波束指向的调整在很小的范围内,故对天线的副瓣及波瓣宽度指标的影响可忽略,从而不会影响到雷达系统的其他性能。     

一种基于超低旁瓣的相控阵天线旁瓣相消算法

本文以口径边缘激励为零的Taylor-■分布函数作为选定波瓣形状,研究了相控阵天线的超低旁瓣设计中的Taylor-■线源综合法,提出了一种基于超低旁瓣的相控阵天线旁瓣相消算法。该算法通过调整Taylor-■分布函数中的设计旁瓣电平和控制旁瓣个数两个输入参数,使波瓣图中的零点对准干扰位置,从而实现相控阵天线的旁瓣相消。仿真结果表明,该算法可以有效地对抗干扰信号,进一步提高了相控阵雷达的空域抗干扰能力。     

X 波段宽带宽角扫描相控阵天线的设计

设计了一种X波段宽带宽角扫描相控阵雷达系统的小型阵列天线,该天线采用Vivaldi 天线做为阵列单元。在考虑阵列单元间的互耦效应下,仿真设计了9*9 小型阵列天线,使该阵列天线在相对带宽达40%下的有源驻波系数小于2,其有源单元方向图E面、H面的波瓣宽度分别达到120度、110度以上。对9*9天线阵的实物进行了加工与测试,测试结果说明了该阵列天线具有良好的宽带宽角扫描特性。因该天线结构简单,重量轻,在相控阵雷达天线中有很大的应用价值。     

自适应阵列天线概述

一、概述自适应阵列天线是一种具有自动适应其周围工作环境能力——即通过自动调整阵列天线单元的幅度和相位,而随时调整天线波瓣图形状使天线处在(或接近处在)某种最最佳工作状态——的一种天线。由于自适应阵列天线具有自动调整天线波瓣图形状的能力,因此可以期望这种阵列天线在主瓣对准(或接近对准)所希望的信号方向的同时,干扰源的方向却处在波瓣零点位置,于是就提高了信噪比。这就意味着自适应阵列天线具有一定的抗干扰能力。在     

海面反射对一维相控阵天线影响的研究

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.     

单脉冲二次监视雷达精度的提高

测量精度是单脉冲二次监视雷达的关键指标,在空中交通日益繁忙的情况下如何提高测量精度是急需解决的问题。文中分析了单脉冲二次监视雷达测量误差的来源和构成,对影响雷达距离测量精度和方位测量精度的主要误差项进行了详细的计算。结合工程实践,给出了提高精度的具体方法。     

Measurement of beat length in polarization-maintaining fibers with external forces method

Beat length is a key parameter for the polarization maintaining fibers (PMFs). Based on a white light scanning Michelson interferometer, the measurement of the phase beat length in PMFs employing the external force is presented. When the linearly polarized light propagates along the principal axis of the PMFs, the polarization coupling occurs at the force position of PMFs. The short and long length PMFs are measured respectively, furthermore, the uniformity of beat length measurement is tested. In the end, the advantages and the disadvantages of the method are discussed in detail.     

Improved method for evaluating antenna performance in mobile environment with consideration of polarization and phase

The paper presents an improved method for evaluating antenna performance in a multipath propagation environment. It demonstrates, theoretically and experimentally, that by using polarization and phase terms of the incident field and the antenna system in the evaluation of the antenna effective gain (AEG), the AEG can be evaluated more efficiently as compared with the conventional method. First, a theoretical expression of the received power is given by using the open-circuit voltage at the antenna terminals, in which both the polarization and the phase of the incident field and antenna gain patterns are explicitly used. Secondly, a newly developed system for the measurement of field parameters, such as polarization and phase as well as amplitude, is introduced. Thirdly, incident field parameters measured in urban and suburban areas of Tokyo are described. It was confirmed that major incident waves were counted in up to five or six directions at a mobile terminal and their polarizations and phases were different depending on the direction of incidence. Also, measurement of the antenna gain patterns of the latest personal digital cellular handset at a talk position finds the dependence of the AEG on polarization and phase, which were significantly varied by the body effect. Finally, the AEG is evaluated based on the method introduced here, and its usefulness is compared with that of the conventional method.     

Polarization Extraction in Planar Near-Field Phaseless Measurements

Near-field measurements typically require both amplitude and phase information to correctly predict the far-field. Unfortunately, there are situations in which the phase data is not available or impractical to obtain. That is why there has been a need for the development of phaseless techniques. Up until now, a number of remarkable solutions to this problem have been proposed by the researcher in different disciplines. Unfortunately, the complete vectorial representation of the field is not investigated in depth. The evaluated cases are usually linearly polarized and only the dominant polarization is investigated while the cross polarized field is usually neglected. This paper addresses the polarization issue in a two-component approach and then proposes a solution to the problem. A searching mechanism, for the incorporation of an appropriate initial guess, is integrated into the well-known, iterative Fourier technique (plane-to-plane) to enhance the algorithm response. Then, using two sets of measured orthogonal information data gathered by two linearly and orthogonally polarized probes, it is shown that with the aid of only a single point amplitude measurement, the polarization characteristics of the antenna can be extracted up to an inherent ambiguity of the right- and left-handedness. In order to have an assessment of the applicability of the proposed method, both linearly and circularly polarized antennas are simulated. Additionally, the method of extracting the polarization from the phaseless data is also verified through a bi-polar near-field measurement.     

雷达极化测量技术

极化信息同雷达信号中的幅度、相位、频率、波形一样,是雷达信号的一个重要参量。不同的辐射源,其极化方式也不同,测量电磁波信号的极化方式对辐射源信号分类、识别都具有重要意义。基于此,提出了用一对正交天线来测量辐射源的极化,通过对此方法进行Matlab仿真实验,并分析实验结果,证明了理论模型和算法的正确性,同时阐述了此方法的优缺点。     

A practical method for measuring the complex polarization ratio of arbitrary antennas

A technique for measuring the complex polarization ratio of an arbitrary antenna is presented. The technique requires the use of two antennas which are not circularly polarized but are otherwise arbitrary. Only reciprocity and linearity are assumed. Six amplitude and phase measurements are performed, two measurements for each pair of antennas. The complex polarization ratio of each antenna is then calculated from the six measurements. The specific details of the measurement technique are described and some measurement results presented.     

Calibration techniques for Olympus 20 GHz switched polarizationsatellite beacon measurements

A measurement of the complete transmission matrix of a slant path using a switched polarization satellite beacon needs to be properly calibrated in both amplitude and phase to yield the best characterization of the hydrometeors which affect propagation. For accuracy, error contributions from the satellite and earth station should be separated and corrected individually. It is shown how this can be achieved by indirect methods which rely on minimal theoretical expectations of the form of the transmission matrix. Methods to calibrate the amplitude and phase offsets of the satellite and receiver, and to assess the satellite polarization purity, are demonstrated using the Olympus satellite at 20 GHz. Small amplitude imbalances in the beacon are found and corrected, but a large correction for an unexpected phase offset is required. Good polarization purity of the beacon is inferred     

单脉冲雷达测角幅相不一致影响及校正

现代雷达型空空导弹广泛采用比幅单脉冲测角方法来确保测角精度需要和差支路保持幅相一致性,但在实际工程中三路接收通道很难保持完全一致。为了不影响导引头的测角性能,分析了导致和差支路不一致的原因及其对测角精度的影响,并提供了一种和差支路幅相不平衡数字校正和失调角归一化处理的方法,并在一套雷达型导引头样机上进行了验证。试验结果表明,这种补偿方法是可行的。     

基于OBA表自适应生成方法的单脉冲二次雷达角度测量

测角精度是单脉冲二次监视雷达的重要指标偏离瞄准轴角(OBA)表反映了天线和差比与目标偏离瞄准轴角度间的关系,是单脉冲二次雷达能够正确测量目标角度的关键所在。针对实际工程中雷达原始OBA表数据无法直接获取,以及无法实际测量天线参数的情况,文中提出了基于OBA表自适应生成方法的单脉冲二次雷达角度测量方法,详细介绍了该方法的基本原理和工程实现步骤。二次雷达录取设备实际工程中的现场联试结果表明：通过误差统计的方法自适应生成的OBA表,为目标方位的提取提供了较精确的修正数据,大大地提高了目标的方位测量精度。     

Reconstruction of the polarization ellipse of the EM field of Telecommunication and broadcast antennas by a fast and low-cost measurement method

A low-cost measurement method for the extraction of the relative phases of the field of base station and broadcast antennas is presented. Our purpose is to determine the polarization of the field at a measurement site using magnitude measurements only. By determining six amplitude components using a spectrum analyzer, the polarization ellipse of the field can be obtained. This low-cost method can be used for outdoor measurements, which is not possible with network analyzers. Using this method and thus knowing the polarization of the incident field we are able to determine more accurately the actual electromagnetic power absorbed in people at a measurement site.