基于光子技术的相控阵雷达天线现场校准技术

为了保证相控阵雷达的性能,它的天线现场校准越来越受到重视。本文首先介绍相控阵雷达天线现场校准的现状,提出目前存在的问题。然后分析光学电磁场探测技术优势,阐述基于光子技术的相控阵雷达天线现场校准实现的可行性,建立了现场校准装置。通过实验验证,该技术能实现对相控阵雷达天线现场校准,具有高精度,对天线的辐射场的影响较小,能满足相控阵雷达天线现场校准要求。     

基于DSP技术的相控阵天线波束控制器设计

相控阵天线是近年来雷达研究的热门课题.相控阵天线的具有波束指向、波束形状快速变化、易于形成多个波束以及可在空间实现信号功率合成的众多优点使其应用范围越来越广泛,比如通信和电子对抗.主要讨论在相控阵天线的通信应用中如何利用DSP技术实现相控阵天线波束的快速扫描.     

基于DDS的收发全DBF相控阵技术

对DDS技术实现任意频率信号产生给予了理论上的解释,介绍了基于DDS的发射全DBF相控阵天线技术的基本思想和性能特点,并给出了4单元发射全DBF相控阵雷达试验系统的和,差波束形成结果。     

一种相控阵雷达天线极化特征的外场测试方法

为了解决相控阵雷达天线极化特征的外场测量问题,研究了极化的幅相测量法和斜天线测试场的布局方法,设计了基于双通道接收技术的相控阵雷达天线极化特征的一种外场测试方法。给出了应用该种方法的测量装置、测量布局、测量内容、测量步骤,分析了测量误差。该种测试方法在相控阵雷达天线极化特征测试任务中得到成功应用,为某武器系统的研制提供了准确的测量数据和宝贵的研究资料。     

基于互耦测试的相控阵天线系统校准研究

本文针对大型相控阵天线系统需要维护和不定期校准的问题,基于相控阵天线振子之间的互耦特性设计了一种通用的校准方法。相对于互耦校准法,文章解决了天线阵面的异形结构和介电常数的不一致性引起的校准偏差,具有更好的通用性;相对于其他方法不需要增加硬件适配,具有更简单的系统复杂度和更好的成本优势。文章通过理论分析和数学推导为该方法提供了支撑,并经过多阵面,多频点验证了该方法的有效性。该方法适用于大多数均匀直线相控阵天线系统,并可推广到平面阵列。     

光学电磁场探测探针标定技术研究

光学电磁场探测探针已逐渐开始在相控阵雷达天线测量等领域应用,它的幅度和相位测量准确度受到大家重视。为了实现对光学电磁场探测探针测量能力准确标定,本文引入电磁场测量探头的标定思路,提出利用矩形金属波导的电场产生标准幅度及相位实现对光学电磁场探测探针标定的方法,建立了标定装置,阐述标定实施过程。通过实验验证,该方法能实现对光学电磁场探测探针标定,精度满足使用要求。     

相控阵跟踪测量雷达测量跟踪特点及应用

雷达的是远距离侦测的眼睛。随着科技的不断发展,各种电子技术不断发展,推动了雷达技术的不断进步,从而使得雷达无论是在测量距离还是测量准确度方面都有着极大的进步。相控阵雷达是一种先进的雷达技术,其测量距离远、准确度高,尤其是在多目标的测量跟踪上具有极强的优势,是部队应用较多也是投入研究力度极大的一种雷达技术。本文在分析了相控阵跟踪测量雷达工作方式与工作特点的基础上对相控阵跟踪测量雷达在工作中所存在的角度、距离捕获与跟踪及丢失处理等方面的信息进行分析阐述,并对相控阵跟踪测量雷达在设计及使用中所存在的一些要点进行了介绍。     

侧装机动车雷达测速仪天线计量关键技术指标研究

在介绍了侧装机动车雷达测速仪基本工作原理的基础上,分析了侧装雷达测速仪在实际工作中存在现场测速误差的原因,研究了满足现场测速误差要求的天线计量关键技术指标:水平主瓣宽度不超过6°,通过2款侧装雷达测速仪在真实交通情况下的现场试验结果,验证了满足天线水平主瓣宽度不超过6°的侧装雷达测速仪在实际工作中的测量结果更为准确可靠,其现场测速误差能够满足我国相关技术法规的要求。     

雷达射频测试系统现场整体计量校准技术研究

传统的集成系统校准是采用单台仪器计量和系统功能检查来完成,原有的系统性能和技术指标是无法保证的,雷达射频测试系统的整体校准是目前急需解决的问题。本文通过设计组配标准化、通用化的现场传递标准件,即通过组配单件传递标准件、组合传递标准件,建立了与雷达射频测试系统相对应的功率、幅度、相位、噪声和反射系数等电参数的工作标准,通过对以上各参数的不确定度分析评定和重复性、稳定性的考核,解决了雷达射频测试系统的量值传递问题,实现了雷达射频测试系统的现场整体校准。     

雷神二次雷达油位告警信号分析

油位探测器作为二次雷达的一个小部件,却发挥着非常重要的作用,一旦出现油位过低告警,雷达的就会立刻停机,从而实现对雷达天线的保护作用,但有时候因探测器的损坏而会出现误报警。文章通过对雷神二次雷达天线系统和油位告警信号的分析,使大家对油位探测器出现故障时的检测和应急措施能有所帮助。     

精密水槽收缩段流场模拟与收缩曲线选型评估

通过求解RANS方程,数值模拟了精密水槽收缩段的流场特性。针对两种不同出口尺寸不同收缩比的收缩段,选取了三种不同的收缩曲线来进行选型评估。根据壁面是否分离、逆压梯度变化缓和程度、出口速度均匀度,来判断不同收缩曲线的优劣。研究表明:对于出口尺寸为250 mm×20 mm、收缩比为30的收缩段,双三次收缩曲线是最优的;对于出口尺寸为250 mm×10 mm、收缩比为60的收缩段,维氏收缩曲线是最优的。本次数值模拟计算的工作可为精密水槽收缩段优化设计工作提供借鉴。     

Diagnostic of phased arrays with faulty elements using the mutual coupling method

The ability to calibrate phased array antennas by utilising the mutual coupling method (MCM), which takes advantage of the mutual coupling effect between adjacent elements, is addressed. The basic assumption of the method is that the mutual coupling between adjacent elements is equal for all elements in the array and its major deficiency is its failure in the case of faulty elements. A parametric study to identify the effect of faulty elements in the array has been conducted. It has been shown that displacement of one element in the array may cause a significant error in the calibration, which affects its radiation characteristics (increase in the far side lobe level). The main contribution is the presentation of the effect of faulty elements in the calibration process and the proposal of a way to detect and bypass the faulty elements in a phased array calibrated by the MCM.     

Metric tensor approach to surveillance analysis of phased array radar

The author shows that the metric tensor gab is sufficient to accurately derive some of the most important system surveillance characteristics of static and rotating phased array radars. The author presents a novel and generalised method using metric spaces on Riemann manifolds as a viable approach for investigating phased array radar system design characteristics that is mathematically tractable and avoids complex iterative and non-analytic procedures.     

Shape calibration of a conformal ultrasound therapy array

A conformal ultrasound phased array prototype with 96 elements was previously calibrated for electronic steering and focusing in a water tank. The procedure for calibrating the shape of this 2D therapy array consists of two steps. First, a least squares triangulation algorithm determines the element coordinates from a 21×21 grid of time delays. The triangulation algorithm also requires temperature measurements to compensate for variations in the speed of sound. Second, a Rayleigh-Sommerfeld formulation of the acoustic radiation integral is aligned to a second grid of measured pressure amplitudes in a least squares sense. This shape calibration procedure, which is applicable to a wide variety of ultrasound phased arrays, was tested on a square array panel consisting of 7-×7-mm elements operating at 617 kHz. The simulated fields generated by an array of 96 equivalent elements are consistent with the measured data, even in the fine structure away from the primary focus and sidelobes. These two calibration steps are sufficient for the simulation model to predict successfully the pressure field generated by this conformal ultrasound phased array prototype     

Self-calibration of large phased-array antennas for radar

Self-calibration of a phased antenna array is required when distortions in the array are not known a priori and cannot be measured, or when turbulence in the propagation medium perturbs the radiation field. Two types of self-calibration procedures are discussed that have proved successful in experimental high-resolution two-dimensional microwave radar imaging. Each extracts information from the backscattered reradiation field to deduce a compensating weight vector for the phased array antenna. The first depends upon the presence of a strong reflector in the field of view of the transmitter. The second calibrates the array from correlation estimates of wavefront samples in the array. The basic algorithm in each group is described, along with two more sophisticated algorithms in the latter class. Two-dimensional radar images of airplanes are shown with resolution comparable to human vision. The performance of each algorithm and comparisons between them are illustrated by these images of targets and by simulation experiments.©1993 John Wiley & Sons Inc     

Multiple-element crosseye

An extension to the traditional two-element array crosseye interferometric electronic jamming technique is investigated. Simulations are performed to obtain excitations for multiple-emitter linear arrays that produce distorted wavefronts over desired regions of space. This results in a greater number of degrees-of-freedom and a better ability to control the desired field pattern. The crosseye effect can be achieved over wider sectors, but only by increasing array power. The technique is extended to two-dimensional arrays and is applicable to multi-function radar antennas. Experimental measurements performed on a four-emitter array demonstrate the feasibility of the technique. Good agreement with predictions is shown     

Partially coherent analysis of imaging and interferometric phased arrays: noise, correlations, and fluctuations

Phased arrays are of considerable importance for far-infrared, submillimeter-wave, and microwave astronomy; they are also being developed for areas as diverse as optical switching, radar, and radio communications. We present a discretized, modal theory of imaging and interferometric phased arrays. It is shown that the average powers, field correlations, power fluctuations, and correlations between power fluctuations at the output ports of an imaging, or interferometric, phased array can be determined for a source in any state of spatial coherence and polarization, once the synthesized beam patterns are known. It is not necessary to know anything about the internal construction of the beam-forming networks; indeed, the beam patterns can be taken from experimental data. The synthesized beams can be nonorthogonal and even linearly dependent. Our theory leads to many conceptual insights and opens the way to a range of new design and simulation techniques.     

Angle density functions for active sensor imaging

A new target density function (TDF) is proposed for active sensor imaging. The TDF, called the angle density function, is studied by utilising the angular distribution of targets at a fixed range. Active sensor imaging based on the angle density function is achieved using a phased array radar system. The phased array system is arranged for stationary radar-stationary target configuration. The imaging algorithm is applied for the whole target area. Instead of pointwise imaging, an approach including the whole target area globally is developed. An advantage of the technique is the use of standard Fourier-based analysis. This makes it possible to use of simple functions for global radar imaging. Although the imaging is accomplished by way of the phased array radars, beamforming is not necessary with the proposed technique.