Phased array calibration

Calibration of a phased array antenna while the antenna is in service can be a complex and time-consuming procedure that affects use of the antenna and imposes an unacceptable overhead on the system. The procedure described herein uses a maximum likelihood algorithm to minimize the number of measurements, thus reducing the impact on the system and shifting the overhead to a remote site     

考虑互耦的相控阵面天线波束形成

本文从实现相控阵面天线低副瓣性能的角度出发,针对在实际的相控阵天线设计中由于阵列天线单元间的互耦效应,用理想的电流分布作为激励往往达不到所期望的副瓣电平要求这一缺陷,首先用矩量法精确分析了考虑互耦影响时相控阵面天线阵元的电流分布,作出归一化电流幅度分布图,仿真实现了阵元互耦对相控阵面天线波束形成的影响效果,接下来用软件的方式补偿互耦所造成的影响,给出补偿的具体步骤,从而完成了相控阵天线波束形成的综合.     

Model based antenna array calibration for smart antenna systems

Model based antenna array calibration is used to remove the antenna array errors or predict the element patterns from the array manifold measured at a small number of directions. The experimental results show that this works very well for one sector angle region even in the presence of modelling errors     

有源相控阵天线的近场校准

为实现对相控阵天线的校准,降低幅相误差和阵元失效对天线性能的影响,提出了一种考虑互耦效应的近场校准方法。在利用近场扫描法完成逐一通道校准的基础上,使用旋转矢量法进行二次校准。在应用旋转矢量法（ REV)时,为使被测信号的变化明显,将大规模相控阵天线分为中间、边缘区域进行分区校准。通过二次校准可判定阵元是否失效,提高相控阵天线的幅相一致性;通过分区校准减小阵元间互耦的影响,缩短校准时间。仿真结果表明：此方法用于大型相控阵的校准具有较高的准确性,可改善校准结果。     

A switched pattern radar antenna array

A procedure to design a switched pattern antenna array is developed and demonstrated on a 16- and eight-element array. The variable spacing of elements allows us to reduce the number of switchable elements to a minimum and to reduce the sidelobes of the effective pattern. Based on this design we have built and tested an eight-element prototype array. Measurements demonstrate the feasibility of the pattern switching concept for improved sidelobe performance.     

Phased array antenna analysis with the hybrid finite element method

A new analysis technique for infinite phased array antennas was developed and demonstrated. It consists of the finite element method (FEM) in combination with integral equation radiation conditions and a novel periodic boundary condition for 3-D FEM grids. Accurate modeling of rectangular, circular and circular-coaxial feeds is accomplished by enforcing continuity between the FEM solution and several waveguide modes across an aperture in the array's ground plane. The radiation condition above the array is enforced by a periodic integral equation in the form of a Floquet mode summation, thus reducing the solution to that of a single array unit cell. The periodic boundary condition at unit cell side walls is enforced through a matrix transformation. That mathematically “folds” opposing side walls onto each other with a phase shift appropriate to the array lattice and scan angle. The unit cell electric field is expanded in vector finite elements. Galerkin's method is used to cast the problem as a matrix equation, which is solved by the conjugate gradient method. A general-purpose computer code was developed and validated for cases of open-ended waveguides, microstrip patches, clad monopoles and printed flared notches, showing that the analysis method is accurate and versatile     

相控阵技术在ETC天线中的应用探讨

为解决因当前ETC使用量变化而引起的若干新问题或新需求,本文将在已得到成功应用和广泛推广的双通信区ETC车道系统集成技术基础上,探讨如何使用相控阵技术来实现ETC天线的技术创新.     

导航卫星阵列天线的快速现场系统校准算法

阵列天线接收处理全球卫星导航信号时,由于天线和射频前端的非理想性,会在不同方向卫星信号中引入不同的载波相位偏差,从而破坏卫星导航接收机距离观测量准确性。针对此问题,提出了一种易实现的卫星导航阵列天线的快速现场系统校准算法。校准过程分为通道校准和天线校准：通过开机和周期进行的通道校准实现阵列天线接收射频前端的通道响应测量;通过与接收处理不同卫星基带数据的数字接收机配合,实现阵列天线的现场阵列流形矢量校准。仿真验证了所提校准算法的正确性和有效性。     

Modeling of active antenna array coupling effects-load variationmethod

This paper presents a simple method for the calculation of the frequency and power variation of an active antenna operated in the presence of a reflecting surface. The situation modeled accounts for interdependent amplitude and phase dynamics and also allows for the extraction of active antenna array coupling coefficients. Analytical and experimental results are presented for both frequency and power variations of an individual element when operated in a strongly coupled imaged array environment. Here the nearest neighbor coupling is shown to be the dominant coupling mechanism     

A broadband antenna array for sea scatter measurements

A nonuniformly spaced array of 25 side-terminated vertical half rhombics is synthesized for the entire high-frequency band. The array is to be used for both transmitting and receiving, as a sky-wave Doppler radar for sea scatter measurements. The array has the capability for providing a maximum transmitting-receiving product gain in the order of 60 dB at low take-off angles, a product azimuth pattern with a nominal beamwidth of2deg, a40degsectoral coverage, a final product sidelobe level of -38 dB, and a grating-lobe level of -30 dB.     

Arbitrary antenna array pattern synthesis using minimax algorithm

A novel approach to arbitrary array pattern synthesis is proposed. It is based on the minimax algorithm originally developed for mismatched filter design for radars with pulse compression. The proposed approach allows the user to define the pattern mainlobe beam width and the sidelobe envelope shape     

一种圆形智能天线阵列与校正网络的设计

论述了一种用于智能天线系统的新型圆形天线阵列与校正网络的设计方法.设计了一种具有良好一致性和高增益全向特性的新型直排印刷振子天线结构,并采用奇偶模分析方法,实现了一种1:8威尔金森功分器/合路器与平行耦合线定向耦合器相结合的校正网络.实验结果证明,研究结果对于3G通信具有很高的实用价值.     

Realizable method of pattern synthesis for array antenna

The problem of realization of an arbitrary current distribution on an broadside array antenna derived from the theory of pattern synthesis is treated and some practical methods are proposed. In these methods, the input voltage of each antenna is transformed by a reactive transformer to take the required value. In one of the methods, experiments to yield Chebyshev patterns were performed and satisfactory results were obtained.     

阵列天线在UXB系统标校中的应用

测量船基地现有标校塔与测量船距离只有980 m,无法满足高频段统一X频段（UXB）系统天线的远场标校距离条件。针对这一难题,提出了一种利用阵列天线合成准平面波的方法,实现在近场距离条件下的远场标校。在现有标校塔上架设安装阵列天线设备,利用16个单喇叭天线组成4×4的天线阵,并通过控制单个喇叭天线元的幅度和相位,使得传播到测量船UXB天线口面处由阵列天线合成的电磁波是准平面波,满足X频段天线远场标校要求。综合运用最优化理论和遗传算法,对阵列天线元的幅度和相位权值进行调节和优化,使得合成的电磁波更为接近准平面波。计算机仿真实验和外场条件下的实际测试均验证了该方法生成的准平面波能够满足UXB天线远场标校要求。     

Phased array antenna analysis using time delay beam steering andhybrid FDTD method

A phased array analysis is presented where the coupling between antenna elements and the beam steering is computed in the time domain using a hybrid finite-difference time-domain (FDTD) and Kirchhoff transform method. The coupled currents are combined with the appropriate time delays to give the total element current, which is then used in conjunction with the voltage excitation to produce the driving point admittance as a function of frequency for a given beam direction     

天线阵元通道失配校正的FPGA实现

基于FPGA的阵元通道校正是自适应天线技术用于实践的重要基础。给出了一种天线阵元通道失配校正方法的FPGA实现方案。仿真结果表明,该实现方案能够有效校正阵元通道失配,现已成功应用于实际的自适应阵系统。     

互耦条件下共形阵列DOA和极化参数的联合估计

针对互耦条件下共形阵列信源方位和极化参数估计问题,结合有源校正给出一种有效的解决方案。论文充分利用锥面共形阵列的特殊结构,通过方向图的坐标系旋转建立了极化敏感共形阵列的互耦误差数据模型,并根据导向矢量与噪声子空间的正交关系建立了子空间拟合算法的优化函数。由于直接求解涉及到复杂的高维参数搜索问题,实现起来难度较大,论文通过合理近似给出了一种简化的线性方程组近似求解方法。仿真实验表明,所给方法能够很好地解决极化敏感共形阵列中的互耦校正问题,信源方位和极化参数联合估计的性能仿真结果进一步验证了算法的有效性。     

Longitudinal coupling between elements in a disc-on-rod antenna array

A general expression is proposed for the coupling of surface wave antennas based on the equivalence principle and on the reciprocity theorem. A particular application is presented for disc-on-rod antennas, and the coupling coefficient is evaluated as a function of frequency, the array parameters and the element parameters. A physical explanation of the results is suggested.     

Analysis of injection-locked antenna array including mutual coupling effects

In this paper, the injection locking performance analysis of dipole antenna array with each element loaded with a two-terminal oscillator is presented. The analysis is based on the nonlinear model of oscillator and the linear model of antenna array considering mutual coupling effects. The locking range of injection signal and the array radiated power are obtained by solving an equivalent multiport network. In general, the solutions include stable and unstable solutions. The Routh-Hurwitz stability criterion is then applied to remove the unstable solutions. Numerical results show that the array performance such as frequency locking range and radiated power by taking into account the array mutual coupling effects is quite different from that of an isolated antenna element. In addition, the influence of antenna element spacing upon array locking parameters in this paper is found to be consistent with other existing theories.     

一种星载阵列天线的高效波束赋形算法

随着有源相控阵和数字波束形成技术的应用, 低轨道卫星通信多波束阵列天线不仅可以形成同时多个固定的对地等通量低旁瓣赋形波束, 还具备了可以随着通信任务需求变化, 动态调整方向图形状的能力.但是目前常用的高性能波束赋形算法, 运算量较大, 收敛速度慢, 优化参数调整复杂, 无法直接应用于在线实时计算.针对上述要求, 提出了一种高效的迭代最小方差方向图综合方法.该方法采用方向图分区域加权逼近和方向图相位去约束技术, 在满足较高的主瓣赋形精度和旁瓣电平控制等指标要求的前提下, 具有迭代过程简单、优化参数少、算法稳健和运算量少等特点, 可以部分满足要求波束方向图动态变化的卫星通信系统权重系数在线计算的需要.