基于改进的迭代FFT的平面稀疏阵列综合方法

针对在原有迭代FFT稀疏阵列综合方法中,其迭代过程容易陷于死循环而必须通过多次重新随机初始化的问题,提出一种改进的迭代FFT稀疏阵列综合方法。该方法具有两层循环迭代,即在原有的迭代FFT方法基础上,增加了内层循环迭代,使得阵因子在满足副瓣约束之后再进行激励大小排序并进行阵列稀疏处理,避免了原有迭代FFT方法容易陷于局部死循环的问题。仿真结果表明,改进的方法比原有的迭代FFT方法可以获得具有更低副瓣电平的平面稀疏薄阵综合结果

A Sidelobe Cancellation Method with Constant Gain

在旁瓣对消系统中,当辅助天线数目大于干扰源数目时,期望信号也被当成一个干扰源而被系统对消掉。一般采用在辅助通道添加阻塞矩阵的方法来解决此问题。然而当期望信号方向与干扰信号方向接近时,采用阻塞矩阵方法会导致合成方向图有较大旁瓣抬升。提出一种新方法,对辅助天线的输出进行线性约束,使辅助天线在期望信号方向形成零陷,从而有效消除辅助通道的期望信号成分,并且具有较好的旁瓣保形能力。通过仿真可以看出,该方法能在保持期望信号方向最大增益的同时,在干扰方向形成非常理想的零陷。In a sidelobe cancellation system,the desired signal can also be eliminated when the number ofauxiliary antennas is larger than the number of interference sources.Generally,this problem can be solvedby adding a blocking matrix on the auxiliary channel.However,the sidelobe shows great uplift when the di-rection of the desired signal is closing on the that of the interference signal.To address the issue,a novelmethod is proposed in this paper,which eliminates the desired signal from the auxiliary antenna by addinga linear constraint on its output.It is observed through simulation that the new method maintains the maxgain in the direction of the desired signal while forming an optimal null in the direction of interference.国家自然科学基金资助项目(61301009); 中央高校基本科研业务费专项资助项目(2012121036); 高等学校博士学科点专项科研基金资助项目(20120121120027); 福建省自然科学基金计划资助项目(2013J01252

阵列天线实现误差对功率方向图扰动的影响分析

对阵列天线工程实现过程中的阵元位置、激励幅度和相位误差进行了分析,在假定各误差为高斯分布的情况下分析了阵列天线功率方向图的期望,并推导了功率方向图方差的理论公式。利用切比雪夫不等式,推导了在给定概率条件下功率方向图上、下边界的理论结果。使用蒙特卡洛模拟,验证了理论推导的正确性和准确度。利用该结果,可以较为准确地预测实际阵列天线中随机实现误差对阵列功率方向图的影响,对于阵列天线工程实践具有重要的指导意义。国家自然科学基金(61871338);;中央高校基本科研业务费(20720160081

Adaptive-Adaptive Sidelobe Cancellation Strategy for Two-dimensional Phased Arrays

传统旁瓣对消方法采用单元天线作为辅助通道,系统对消输出的信噪比较低,且合成阵列存在较高的副瓣抬升隐患。针对二维稀疏阵列的应用特点,提出一种新的自适应—自适应旁瓣对消策略。该方法取代了传统方法中使用的单元天线以及数字加权方法,使用小型阵列作为辅助通道和射频加权,并借助辅助通道对干扰方向进行估计,根据估计得到的干扰方向信息对辅助子阵列内部的射频加权系数进行调整,使得辅助通道的波束最大可能地对准干扰方向。最后利用恒增益对消技术,实现主阵列中的旁瓣对消。仿真实验结果表明了该方法的有效性和优势。The traditional adaptive sidelobe cancellation method uses single antenna as assistant channel,so the signal to noise ratio( SNR) of system output is small,and it is possible to uplift the sidelobe in synthetic array. In view of application feature of two-dimensional sparse array,a new method named adaptive-adaptive sidelobe cancellation is proposed in this paper. The new method replaces the single antenna with small synthetic arrays as assistant channel and replaces digital weighting method with RF weighting method,and it estimates the direction of the jamming with assistant channel. According to the information about the direction,the new method adjusts the RF weight of assistant channel,and makes the beam of assistant channel align the jamming directions. The sidelobe cancellation method with constant gain is used to perform the sidelobe cancellation. The simulation results prove the effectiveness and advantages of the proposed method.国家自然科学基金资助项目(61301009);; 福建省自然科学基金计划资助项目(2013J01252);; 高等学校博士学科点专项科研基金资助项目(20120121120027

Modified GA-FFT for Synthesizing Shaped Pattern of Unequally Spaced Array in Presence of Mutual Coupling

该文提出了一种虚拟的最小均方有源单元方向图展开方法,将不等间隔阵列的有源方向图展开为一个虚拟的均匀间隔阵列的若干单元辐射的叠加。通过该方法,对包含阵元耦合效应的不等间隔阵列方向图,可以使用快速傅里叶变换进行加速计算。并且,该文将这个方法与遗传算法(GA)相结合,得到一种改进的GA-FFT方法,可以应用于解决含阵元互耦的不均匀间隔阵列的赋形波束综合问题。最后,分别对不等间隔的偶极子阵列平顶方向图及微带阵列的余割平方方向图进行了综合,结果表明所提方法的有效性和优势。A new Virtual Least-Square Active Element Pattern Expansion(VLS-AEPE) method is presented in this paper, which considers each active element pattern of an unequally spaced array as the one radiated by some of equally spaced elements of a virtual array. Using the help of this method, the pattern of an unequally spaced array including mutual coupling can be efficiently calculated by FFT. In addition, this method is combined with the Genetic Algorithm(GA) to deal with the shaped pattern synthesis problem for unequally spaced linear arrays. Two synthesis experiments including the synthesis of flat-top pattern for an unequally spaced dipole array and the synthesis of cosec-squared pattern for an unequally spaced microstrip array are conducted to verify the effectiveness and advantages of the proposed algorithm.国家自然科学基金(61301009);; 中央高校基本科研业务费(20720160081)~

Optimal Directivity Synthesis of an Arbitrary Array Subject to Sidelobe and Cross-Polarization Constraints

本文根据给定的期望极化方向,定义了扫描波束的期望主极化和交叉极化方向,并进一步给出了主极化方向性系数的定义,它可以更为准确的表征天线集中辐射主极; 化分量的程度.在没有副瓣约束和交叉极化约束的条件下,给出了任意阵列主极化方向性系数最优解的解析表达式.并且,在含副瓣约束、零陷约束以及交叉极化约; 束的条件下,我们发展了一种基于凸优化的高效数值综合方法,实现多约束条件下的主极化方向性系数的优化.数值阵列综合结果表明了本文所提出的最优主极化方; 向性系数解析解的正确性,以及这种可以综合考虑副瓣约束、零陷约束和交叉极化约束的数值方向性优化方法的有效性.Definitions of the desired co-polarization and cross-polarization; directions are given for a scanned beampattern according to a desired; polarization direction. Furthermore, the co-polarization directivity is; defined to more accurately represents the degree of the concentration of; co-polarization field over the total radiated power. With this; definition, the co-polarization directivity can be optimized. Its; analytical expression can be derived when no more pattern constraints; exist. In more general cases in which the constraints on the sidelobe; level,nulling points and cross-polarization level exist, an efficient; numerical algorithm based on convex optimization is proposed. Some; numerical synthesis experiments are conducted, and the results show the; effectiveness and robustness of the proposed synthesis techniques.国家自然科学基

Combining triangle Gaussian integration and modified NUFFT for evaluating two-dimensional Fourier transform integrals

Fundamental Research Funds for the Central Universities [2012121036]; Specialized Research Fund for the Doctoral Program of Higher Education [20120121120027]; Natural Science Foundation of Fujian Province of China [2013J01252]; NSFC [61301009, 41240029]; Science and Technology Development Foundation of Xiamen CityThe regular fast Fourier transform (FFT) requires a uniform Cartesian orthogonal grid which has considerable stair-casing errors when dealing with the function having an arbitrary shape boundary. The recently proposed two-dimensional discontinuous fast Fourier transform (2D-DFFT) can overcome this problem by using triangle mesh discretization and Gaussian numerical integration. However, the interpolation is used for the function data in the original 2D-DFFT, which reduces the accuracy performance especially for the case of oscillating functions. This work presents a useful modification of the original 2D-DFFT by removing the requirement of function interpolation to obtain significant accuracy improvement. In addition, the modified 2D nonuniform fast Fourier transform (NUFFT) with real-valued least-square interpolation coefficients are developed to speed up the computation of numerical Fourier transform over the triangle mesh. Numerical experiments are conducted to demonstrate the effectiveness and advantages of the proposed algorithms. (C) 2013 Elsevier GmbH. All rights reserved

Combining triangle Gaussian integration and modified NUFFT for evaluating two-dimensional Fourier transform integrals

The regular fast Fourier transform (FFT) requires a uniform Cartesian orthogonal grid which has considerable stair-casing errors when dealing with the function having an arbitrary shape boundary. The recently proposed two-dimensional discontinuous fast Fourier transform (2D-DFFT) can overcome this problem by using triangle mesh discretization and Gaussian numerical integration. However, the interpolation is used for the function data in the original 2D-DFFT, which reduces the accuracy performance especially for the case of oscillating functions. This work presents a useful modification of the original 2D-DFFT by removing the requirement of function interpolation to obtain significant accuracy improvement. In addition, the modified 2D nonuniform fast Fourier transform (NUFFT) with real-valued least-square interpolation coefficients are developed to speed up the computation of numerical Fourier transform over the triangle mesh. Numerical experiments are conducted to demonstrate the effectiveness and advantages of the proposed algorithms. ? 2013 Elsevier GmbH. All rights reserved

Reducing the Number of Elements in Multiple-Pattern Linear Arrays by the Extended Matrix Pencil Methods

Fundamental Research Funds for the Central Universities [2012121036]; Specialized Research Fund for the Doctoral Program of Higher Education [20120121120027]; National Natural Science Foundation of China (NSFC) [61231001, 61301009, 41240029]; NSF of Fujian Province [2013J01252]Previously, the matrix pencil method (MPM) and the forward-backward MPM (FBMPM) were used to effectively reduce the number of antenna elements in the single-pattern linear arrays. This work extends the MPM and FBMPM-based synthesis methods to the synthesis of multiple-pattern linear arrays with a smaller number of elements. The extended MPM (resp., the extended FBMPM) method organizes all the multiple pattern data into a composite Hankel (resp., composite Hankel-Toeplitz) matrix from which the minimum number of elements and the common poles corresponding to element positions can be obtained with similar processing used in the original MPM or FBMPM synthesis method. In particular, the extended FBMPM inherits the advantage of the original FBMPM that a useful restriction is put on the distribution of poles, which makes the element positions obtained much more accurate and robust. Numerical experiments are conducted to validate the effectiveness and robustness of the proposed methods. For the tested cases, the element saving is about 20% similar to 25% for reconfigurable shaped patterns, and can be even more for electrically large linear arrays with scanned pencil-beams

Generalization of matrix pencil methods to the synthesis of wideband aperiodic linear arrays with frequency-invariant patterns

Conference Name:2014 31th URSI General Assembly and Scientific Symposium, URSI GASS 2014. Conference Address: Beijing, China. Time:August 16, 2014 - August 23, 2014.The problem of generalizing the matrix pencil methods (MPM) to the synthesis of wideband aperiodic arrays with frequency-invariant (FI) patterns is considered. A new pattern sampling strategy is presented to obtain the multiple pattern data of different frequencies having the common poles. The generalized MPM (GMPM) and its forward-backward version (GFBMPM) are developed to find the best common element positions for different frequencies, which can significantly reduce the number of elements required for the desired pattern shape. Numerical examples are presented to validate the effectiveness and advantages of the proposed methods