任意拓扑结构的耦合振荡器阵列及其在共形阵中的应用

提出了一种利用耦合振荡器阵列实现共形相控阵天线波束扫描的新方法。建立了任意拓扑结构的耦合振荡器阵列幅度和相位动力学方程,采用图论的方法分析了稳态相位方程解的唯一存在性和稳定性,通过控制振荡器每个单元的自由振荡频率,对相位进行加权,实现了共形相控阵天线无移相器的波束扫描,最后对圆柱形耦合振荡器阵列天线进行了数值仿真,验证了该方法的可行性。     

共形阵列天线单元极化形式的优化设计

由于共形载体曲率的影响,共形阵列天线的阵列流形具有多极化特性.为了利用共形天线阵列流形的多极化特性,提升阵列对空间目标参数的估计性能,将天线单元的极化参数引入到导向矢量建模中.更加完整地论述了共形天线阵列流形的特点.在此基础上.建立了优化设计天线单元极化形式的目标函数,基于交替优化思想.给出了共形阵列中各天线单元最优极...     

单脉冲双极化天线阵列设计

文章研究了单脉冲双极化天线阵列。天线阵混合馈电微带单元由共面微带线馈电和缝隙耦合微带线馈电两者结合形成,"十"字形微带单脉冲比较器与天线阵同面,具有结构紧凑、加工方便和成本低的优点。经仿真验证,在工作频带内其辐射单元双端口隔离度高于34dB;并且2个极化端口在其对应主平面方向的副瓣电平均低于-20dB。天线可适用于新一代多极化雷达系统。     

基于二元交替激励的一维线阵控制方法

为了得到一种简单有效的阵列天线方向图控制方法,首先,从二元阵天线的结构及方向图入手,结合方向图乘积定理,通过对阵元天线激励幅度和相位的控制,得出了一种基于二元阵交替激励的阵列天线方向图调控方法;然后,结合理论推导,对真实的阵列天线进行了激励控制实验,并对实验数据的分析,重点研究了阵列天线归一化方向图的变化,证实所研究方法的可行性。     

参考阵元可自适应调整的阵列天线抗干扰方法

针对导航接收机抗干扰阵列天线在某些干扰来向存在抗干扰效果减弱的问题,建立了基于功率倒置算法的阵列信号处理模型,提出一种参考阵元可自适应调整的阵列天线抗干扰方法.以四阵元均匀圆阵为例进行了仿真验证,仿真结果表明,相比于参考阵元固定的功率倒置算法,此方法能够很好地解决部分干扰来向抗干扰效果减弱的问题.     

一种低副瓣波纹喇叭天线的设计与实现

文章设计了一种高斯分布的波纹喇叭天线,具有增益高、转换效率高、交叉极化低、相位中心不随频率变化的特点。该天线采用正交馈电,结构简单紧凑,以双线极化或圆极化方式工作。根据天线设计参数,建立了天线模型,进行了优化设计。仿真和实测结果表明,天线在频率34～36 GHz范围内,增益大于20dBi,方向图在E面和H面具有良好对称性,副瓣电平不大于-26 d B,驻波比小于1.5,整体性能满足工程应用要求。     

弹载共形相控阵天线拓扑结构分析

以弹载多模复合制导雷达导引头为应用背景,在未考虑极化的情况下,首先建立了任意有向阵列的方向图函数;然后,采用同心圆等角度、同心圆等间距以及矩形栅格 3种不同配置方式,建立了锥面共形相控阵天线模型,推导了不同配置方式下天线阵列方向图函数;通过比较其方位面及俯仰面的副瓣电平,得出结论:同心圆等间距配置方式是锥面共形相控阵雷达导引头天线单元的最优配置方式。     

基于遗传算法的平面相控阵天线综合

利用遗传算法对平面相控阵天线进行了综合，在一定的频率范围内对天线阵的阵元间距、馈电流幅度和相位进行了优化。这种方法在抑制副瓣电平的同时，使天线阵的相对带宽得到了较大的提高。良好的仿真结果表明，该遗传算法在阵列天线方向图综合中的应用是有效的，有良好的应用前景。     

极化角对跟踪接收机相位影响分析

根据卫星通信中遇到的极化问题及其对移动地面站的影响,针对不同极化卫星间的差异,从电磁场理论中极化的定义和分类出发,给出不同极化电磁波电场信号表示方法,以某型移动卫通站天线馈源结构为例,介绍了不同状态下极化工作方式和线极化方式中线极化面调整的机理,然后结合单通道单脉冲跟踪接收机工作原理,对天线跟踪水平极化信标时线极化角与跟踪接收机相位间的关系进行了详细分析,为解决实际应用中遇到的跟踪接收机相位漂移问题提供了技术依据。     

基于耦合振荡器阵列的天线接收技术

论文根据耦合振荡器阵列提供一组均匀相位分布本振信号的接收原理,推导了一维线性和二维矩形耦合本振阵列产生均匀相位分布的控制方法,并对耦合本振阵列的稳定性进行了分析,为耦合振荡器阵列在天线接收技术中的应用提供理论参考。     

Performance of phased-array antennas with mechanical errors

The performance of planar phase-array antennas with mechanical errors is investigated. Errors in array element positions as a result of structural distortions are considered as deterministic and predictable. Detailed calculations for two assumed modes of distortion reveal that their effects on antenna performance are the loss of peak response in the scan direction and the broadening of the mainlobe, while the far-out sidelobe structure remains relatively intact. For large antennas, performance improvement can be expected by suitable phase compensation. Performance of antennas with random errors in their element positions must be treated statistically. Expressions of average directivity and sidelobe level corresponding to arbitrary error magnitudes in element position, amplitude and phase of excitation as well as finite rate of failure of element modules were derived and verified by direct numerical calculations from the antenna directivity patterns. For a planar phased-array antenna typical for space-based radars, the standard deviation of element position errors must not exceed 1% of the operating wavelength in order to maintain a -10 dBi sidelobe level     

Direction finding with a four-element Adcock-Butler matrix antennaarray

The conventional analog Adcock-Butler matrix (ABM) antenna array direction finder suffers from systemic errors, component matching problems, and bandwidth limitations. Three digital bearing estimators are developed as candidates to replace the analog signal processing portion of the ABM. Using the same antenna array, they perform all signal processing in the frequency domain, thereby benefitting from the computational efficiency of the fast Fourier transform (FFT) algorithm. The first estimator requires two analog-to-digital converters (A-D) and three antenna elements. It multiplies the difference between the discrete Fourier transforms (DFTs) of the output signals from two antenna elements with that from a third antenna element. At each frequency component, the phase of this product is a function of the bearing. A weighted least squares (LS) fit through all the phase components then gives a bearing estimate. The second estimator is similar to the first but uses three A-D and all four antenna elements. The output signal from the additional antenna element provides an independent estimate of the weights for the LS fit, giving an improvement in accuracy. The third estimator applies the physical constraint existing between the time-difference-of-arrival (TDOA) of a signal intercepted by two perpendicular sets of antenna elements. This yields a better estimator than simple averaging of the bearing from each set of antenna elements. The simulation studies used sinusoids and broadband signals to corroborate the theoretical treatment and demonstrate the accuracy achievable with these estimators. All three direction finders have superior performance in comparison with the analog ABM     

Analysis and Design of Antennas for Air Traffic Collision Avoidance Systems

The analysis and design procedure of an antenna for a CW Doppler radar system being developed for pilot warning of midair collision hazards is presented. The antenna consists of two vertical arrays of half-wavelength dipoles mounted near a circular conducting cylinder. Each vertical array is composed of three vertical dipoles. Each array provides relatively uniform illumination (2-3 dB) in the forward 180 angular segment of the horizontal plane and approximately + 10-150 coverage in the vertical plane. The antenna could be used in a two-mode operation, either in a standard monopulse radar system (sum and difference amplitude patterns) or in a system where amplitude and phase are the measurable quantities.     

基于仿生原理的超角分辨天线阵设计

以昆虫的声波超分辨定位原理为基础,提出了对应的电小仿生天线阵系统,增强了电小天线阵的角度分辨能力。在具体设计过程中,运用奇偶模分析方法,推导出在不损失功率的条件下,相位差放大因子与天线阵元的阻抗和互耦之间的约束关系,与此同时提出了可获得更大相位差放大因子的设计方法。以此理论为基础,设计了一个二元电小天线阵,仿真并测试了其角度分辨性能,测试结果与理论分析一致,有力地验证了仿生天线阵理论的正确性与设计方法的有效性。     

The Segmented Aperture Synthetic Aperture Radar (SASAR)

A new concept in synthetic aperture radar, called SASAR, which uses a segmented aperture, is described. Use of the segmented aperture allows appreciable extra receiving antenna gain to be realized. Each subarray of the receive antenna is equal in length to the transmit antenna; the system performance is increased approximately by a factor equal to the number of subarrays. To allow array combination of the subarray signal outputs requires a phase-shift factor (varying with azimuth) to be applied to each subarray signal. A digital implementation of this preprocessor is sketched out; it uses a push-down storage stack to store the range histories for a synthetic aperture from each subarray. Appropriate phase shifts are added to the stacks and a sum of stack values then provides the combined output range history sequence. Possibilities of using analog delay lines for preprocessing are also discussed. Pattern errors due to subarray size and receive array near field are examined and constraints are given.     

Characterizing radar emissions using a robust countermeasurereceiver

The author presents a high-sensitivity signal processing approach for detecting and estimating the angle of arrival (AOA), frequency and pulse repetition frequency (PRF) of multiple radar emitters using broadband interferometers. Two time series are generated using information embedded in the sampled cross correlation of the signals obtained from three antenna elements (i.e. two base legs). The phase and amplitude of a complex Fourier transform of these two time series with respect to the sampling clock are used to estimate the AOA and PRF of pulsed emitters     

基于阵元激励幅度分档的赋形波束方向图综合

提出了一种新型的基于幅度分档的赋形波束方向图综合算法。该算法共分为3步。首先,使用传统方向图综合方法如交替投影得到波束的无幅值限制的阵元激励;然后,使用概率密度理论对得到的阵元激励幅度进行处理得到量化的阵元激励幅度,最后,通过量化阵元激励幅度,使用半正定松弛（SDR）方法得到阵元激励的相位分布。上述步骤中,如何使用概率密度理论得到量化的阵元激励幅度是3步中较为重要的一步。将阵元激励幅度用概率密度变量进行替代,通过事先设定的阵元激励幅度档位个数,以及每个阵元激励幅度落在相应档位时取值的概率,可以得到含有概率密度变量的综合方向图表达式。最小化含有概率密度变量的综合方向图与理想方向图的功率之差即可得到量化的阵元激励幅度。使用概率密度理论得到量化阵元激励幅度的优势在于,可以根据任意形状的阵面和阵元栅格排布来划分幅度的档位区间,从而有着更广泛的适用性。在例证部分,通过多组算例的仿真,以及与一些对算法性能的分析,所提算法验证了其在综合效果上的优越性。     

The Effect of Rotating Antennas and Signal Polarization on Doppler Shift

A study is made of a transmitting antenna spinning relative to a receiving antenna, showing that the received signal undergoes a phase shift which depends upon the relative orientation and the ellipticity conditions of the two antennas. It is shown that this phase shift is important in Doppler distance measuring equipment because it must not be confused with the phase shift caused by the changing distance between the antennas.