一种双波束相控阵天线的设计与实现

介绍了一种双波束相控阵天线,阐述了其工作原理、设计方法及实测结果。该天线阵工作于P波段,用于雷达干扰发射系统,发射波束为方位同时双波束,并且每个波束均可独立电扫描,实现了同时对多目标、多方位的雷达干扰。     

基于DDS的有源相控阵天线

有源相控阵天线不仅能提高通信系统的性能,而且还能扩充其功能,所以在通信领域的应用越来越广泛.本文介绍一种没有高频移相器的8单元有源相控阵天线系统,它由平面天线阵、数字T/R组件、接收DBF和系统控制分析软件等组成.其基本原理是在发射模式下,利用直接数字合成(DDS)代替传统的高频移相器和衰减器.由于DDS的工作频率比较低,需要通过上变频到系统所需要的工作频率(2.0GHz).在发射模式下,通过控制DDS完成发射波束形成所必需的幅度、相位加权和上变频所必需的本振信号;在接收模式下,则利用DDS技术产生接收信号下变频所必需的本振信号,然后采用DBF技术形成接收波束.文中详细介绍了基于DDS的有源相控阵天线的实现方法和实验结果.通过8单元基于DDS的有源相控阵天线系统的研究,证实了DDS技术在相控阵天线中应用的显著优点和相控阵天线在通信领域具有潜在应用市场.     

基于防撞雷达的分集相控阵设计方法

常规相控阵雷达通过移相发射空间合成的相参信号形成能量聚集的天线方向图,由于收发天线复用因此所合成的天线孔径要低于收发分置的MIMO雷达。该文首先通过理论推导MIMO雷达在探测性能上和相控阵雷达的一致性及区别,指出MIMO雷达的实质优势在于发射波束的数字赋形。然后设计一种基于防撞雷达的分集相控阵,发射端采用相控体制,接收端采用DBF数字波束形成,通过分析移相器位数对该雷达性能的约束,证明在指定波束指向上该雷达在避免产生正交信号的前提下能达到和MIMO雷达相同的虚拟孔径性能。最后通过计算机仿真,验证该方法的有效性和可行性。采用该雷达体制在保证合成波束宽度的前提下,能有效降低接收通道数,从而有效降低雷达成本并提高通道一致性。     

On-board non-linear circuitry for Ku-band active arrays

Active phased arrays will play an important role in future satellite communications, because of the system flexibility and potential reconfigurability that they may provide. Therefore, an investigation of the relationship existing between payload characteristics and the synthesis parameters of this kind of antenna may constitute a helpful tool. To this end, a parametric analysis of the on-board non-linear circuitry of the transmitting system (power and up-converter sections) has been carried out, establishing the dependence of the mass and DC power demand on the number of beams and feeds of the transmitting phased array. The parametric investigation has been, in particular, applied to an active imaging phased array and an active direct radiating phased array whose suitability to provide a multibeam coverage of Western Europe at K_u band has been demonstrated within an ESA/ESTEC contract. This paper describes the parametric approach followed in the investigation of the on-board non-linear subsystems of the active transmitting phased arrays. The assumed circuitry configurations are widely commented, and the parametric curves for the case of imaging and direct radiating phased arrays are reported.     

Active phased arrays for multi-beam earth coverage

The anticipated density of satellite communications traffic with mobiles will require multi-beam earth coverage. Multiple beams can be generated from reflector antennas with multiple feeds or from a phased array aperture. The constraints on each system are discussed, and it is concluded that for more than about seven beams the best system involves a phased array antenna, particularly if reconfigurability of the beams may be required. Active phased arrays, with a power amplifier at each radiating element offer advantages in reliability and may indeed be the only way of handling the large total radiated power of future systems at acceptable levels of intermodulation.     

The use of current sources in wire moment-method analysis and thefeed-network interaction with an array

Discusses the 1.8 MHz transmitting phased array antenna of Christman (2000). The present author presents an NEC-4 analysis of the BOP (both arrays fed out of phase) and BIP (both arrays fed in phase) cases. Antenna radiation patterns are shown     

Formation of a Receiving Beam in a Receiving and Transmitting Phased X-Band Antenna Arrays for Tracking a Group of Targets at Close Distances with Simultaneous Radar Illumination

An approach is proposed for the implementation of parallel in time reception of signals from a group of targets simultaneously illuminated by radar station, which is based on the use of an analog transmit–receive phased antenna array. One of the possible schemes for constructing a phased antenna array for working on a group of targets is considered. The principle of controlling the phase distribution on the opening in the reception mode is considered. Estimates are given for the decrease in the potential of the radar and the reduction in the detection range when applying the described method. The case of formation of four receiving beams is considered. The results of calculations of total, difference radiation patterns, and direction-finding characteristics for each of the four beams are presented.

     

Sonic microwave-antenna simulator

A simulator is described which generates and transmits beams of audible sound energy which are mathematically similar to those generated in a microwave system. The simulator's transmitting elements form a phased array that electronically focuses and steers coherent sonic beams allowing microwave antenna pattern generation to be studied acoustically in a laboratory environment. Each of the transmitting elements is independently software controllable in amplitude and phase. This flexibility permits a wide range of antenna patterns to be simulated. Independent phase control of each individual transmitting element also allows the simulator to be focused at any point in space. Focusing the simulator to a point in its near field allows far-field antenna patterns to be generated close to the array for ease of measurement.     

Ka频段大规模相控阵稀疏布阵算法设计与应用

针对大规模卫星通信相控阵天线在阵元受发射/接收组件、驱动放大器等布局限制条件下的稀疏布阵问题,提出了一种基于极限微扰法的随机稀疏布阵算法。通过极限微扰率和随机稀疏算法的迭代应用,能够较容易地收敛到目标稀疏率下的稀疏阵列分布,且能得到均匀的稀疏布阵结果,改善相控阵天线由于局部过热导致的散热困难的问题。基于此方法,对满阵为4 096阵元的大规模相控阵天线进行了稀疏化设计,最终得到1 552阵元的稀疏阵。仿真和实测结果显示通过该算法能获得较好的阵列方向图结果,在方位角0°~360°、俯仰角0°~60°范围内副瓣均低于-16 dB。     

Quadratic antenna systems and noise excited antennas

A quadratic receiving antenna system is defined as a multiport antenna whose outputs are passed through square-law detectors, or, in pair, through correlators (product detectors). These detected signals are then linearly combined with different weights to give the output or response of the receiving system. A reciprocity relation is derived which relates the electromagnetic field radiated by a multiport transmitting antenna excited by quasi-monochromatic noise sources to the response of a quadratic receiving antenna system. The noise sources exciting the transmitting antenna may be independent or they may be correlated. In general, the radiated field is partially polarized. The weights used in combining the signals from the square-law detectors and the correlators in the associated receiving system are determined by the intensities of, and the correlations between, the noise sources exciting the transmitting antennas. Practical use has been made of the derived reciprocity relation. The radiation properties of noise-excited multiport antennas have been determined by measurements made on the associated quadratic receiving system.     

A High Resolution Wide Swath SAR method based on intra-pulse null steering and MIMO

High Resolution Wide Swath （HRWS） Synthetic Aperture Radar （SAR） often suffers from low Signal-to-Noise Ratio （SNR） due to small transmitting antenna, especially in phased array antenna systems. Digital Beam Forming （DBF） based on Single Input and Multiple Output （SIMO） achieves receiving array gain at the cost of increasing data rate. This letter proposes a new HRWS SAR method, which employs intra-pulse null steering to get receiving gain in elevation and decrease the data rate, and Multiple Input and Multiple Output （MIMO） using Space-Time Block Coding （STBC） in azimuth to get transmitting gain and receiving array gain simultaneously. The feasibility is verified by deduction and simulations.     

基于软件无线电的相控阵雷达系统研究

主要论述了相控阵雷达系统中软件无线电的实现结构，首先从软件无线电的概念出发，论述了在相控阵雷达系统中采用软件无线电技术的必要性和可能性；其次详细地论述了相控阵雷达系统中软件无线电的实现形式：即天线子系统、收/发子系统、信号处理子系统。最后对软件无线电技术在现代雷达中的发展进行了展望。     

Spatial correlations in adaptive arrays

A receiving array antenna can steer its main beam toward any direction by adjusting the complex weight in each element. However it cannot always steer one beam and one null toward two prespecified directions simultaneously with a single set of weights. The ability for an array to steer one beam and one or more nulls simultaneously is determined by five factors: 1) element positions, 2) orientations of elements, 3) antenna patterns of elements, 4) polarizations of signals, and 5) directions of the beams and/or nulls. A coefficient is defined, called spatial correlation, which includes these factors and completely characterizes array beam pointing and nulling. Its application to adaptive arrays is demonstrated. The adaptive array performance is dominated by this coefficient and can be improved by properly choosing the first three factors. Several examples on the selection of element placement in adaptive arrays are presented.     

有源相控阵天线发射方向图测试简易方法

有源相控阵天线需要对接收和发射两种状态的天线方向图进行测试。现有天线测试远场只能进行接收态的方向图测试,介绍了在远场进行发射态方向图测试的一种简易方法。利用远场的测试转台和发射喇叭,使用频谱分析仪接收有源相控阵天线发射的数据,编制测试软件采集处理数据,即能实现有源相控阵天线发射方向图的测试。该测试方法简单易行。     

用于室内无线通信的新型多波束天线阵列

本文提出了一种低剖面、低成本的多波束天线阵列的设计方法。与传统的切换多波束天线设计相比,新设计可以在不切换的情况下同时实现多个波束。多波束由一个简单的馈电网络实现,馈电网络的激励分配由最大功率传输效率法和加权对角矩阵确定。通过调整测试接收天线的加权系数,可以实现8个方向不同辐射强度的多个波束。天线的工作中心频率为5.8 GHz,天线系统主要由辐射部分和馈电部分组成,分别置于两个不同的堆叠基板上,通过同轴馈电。利用八波束共存的优势,可提供全面覆盖和改进链路预算,适用于双向隧道或室内使用的无线通信系统。     

相控阵天线单元研究

文章研究了一种新型的、带有高阻抗环检测天线的印刷偶极子相控阵天线单元。其特点是可利用检测天线与单元天线之间的传输关系，准确反映单元天线的动态特性。这种天线的应用对研究相控阵天线的实时检测问题十分有用     

稀疏MIMO雷达实孔径三维成像技术

针对任意的多输入多输出(multiple-input multiple-output, MIMO)稀疏阵列提出了MIMO单快拍成像模式和相控阵多帧联合成像模式两种三维成像方法,并对两种模式下角度分辨率及信噪比(signal noise ratio, SNR) 进行了对比. MIMO单快拍成像模式角度分辨率等价于收发联合等效阵列;相控阵多帧联合成像模式的方向图等于发射方向图与接收方向图的乘积,同样也能获得收发联合等效阵列的角度分辨率;相控阵多帧联合成像模式与MIMO单快拍成像模式的SNR的比值为发射阵列数量. 讨论了稀疏阵列与均匀满阵之间的区别与联系,稀疏阵列的波束方向图等价于均匀满阵的二维加窗快速傅里叶变换(fast Fourier transform, FFT),加窗使稀疏阵列方向图展宽. MIMO单块拍成像模式适用于对实时性要求高的应用场景,相控阵多帧联合成像模式适用于对SNR要求高的应用场景.     

Dipole and slot elements and arrays on semi-infinite substrates

The printed dipole or slot antenna on a semi-infinite substrate and infinite phased arrays of these elements are investigated. The solution is based on the moment method in the Fourier transform domain. The generalized impedance or admittance matrix can be expressed in rapidly converging infinite-integral or infinite-summation forms, allowing the accurate determination of the current distributions. Using the present formulation, the input impedance, resonant length, and radiation pattern for the isolated antennas, and the reflection coefficient for infinite phased arrays, are calculated.     

通信网络的可靠性评估

通信网络的可靠性评估是一个难题。目前人们只对环型网和树型网进行可靠性分析。本文首先定义了通信网络的可靠性，依据图论提出了网络生成树的计算方法，以及网络可靠度的估算公式。最后给出了一个栅格型网的可靠度估算示例。