自适应阵列智能天线抗干扰性能研究

分析了自适应阵列智能天线的基本原理,给出了基于复数LMS算法的自适应阵列智能天线波束形成方法,同时对该智能天线抗干扰性能进行了Matlab仿真,理论分析和仿真结果表明:自适应阵列智能天线阵能够实时地调整天线方向,使天线的主波束对准期望信号方向,零陷对准干扰方向从而抑制干扰信号,在干扰和低信噪比环境下,接收端使用智能天线可以大大降低误码率,该智能天线具有较强的抗干扰性能。     

基于混沌粒子群算法的阵列天线容差分析

研究阵列天线性能优化设计,针对阵列天线幅相误差对天线性能的影响,传统的阵列天线容差分析采用统计理论方法,前提需要假设幅相误差服从某种概率分布,导致不同分布的幅相误差对应不同的结论形式,并且公式推导过程复杂.为了在建立阵列天线最坏情况容差分析的数学模型,提出了一种混沌粒子群算法简单实用的阵列天线最坏情况容差分析方法.通过在粒子群算法中利用混沌技术优化初始种群,并对位置更新时引入混沌扰动项和位置更新后进行边界约束,进行仿真,提高了粒子群算法的全局搜索能力.结果验证了算法在最坏情况分析时,可以得到在准确性和稳定性方面的优化结果.     

基于改进的GABP算法优化5G天线阵列

为了加快天线建模速度,针对现有天线设计软件天线参数优化速度过慢问题进行了建模研究。首先通过几种常用的启发式算法优化后的多层前馈（Back propagation,BP）神经网络对天线参数进行优化比较,并对其中最优的算法遗传算法优化BP（Genetic algorithm BP,GABP）神经网络算法进行深度改进。其次采用自适应算法和模拟退火算法优化算法对GABP进行优化。最终通过模拟试验验证出自适应GABP算法对于天线参数优化的误差最小。该研究为天线设计软件中天线优化方法提供了一种误差较小的新方法,拥有更高的预测准确度,拟合速度也大大提升。实验对比证明了该算法的可行性。     

一种L/C双频段盘锥和微带阵列的天线综合设计

设计了一种工作于L、C频段的复合天线,天线采用盘锥天线和微带阵列叠层复合设计。盘锥天线通过加载金属短路柱实现小型化和宽频化,在0.95～1.6 GHz辐射水平全向电磁波;微带天线采用2×2小型化阵列,在4.25～4.35GHz实现高增益定向电磁波辐射。该复合天线内嵌安装于金属腔体内,腔体直径为200mm,高度为26.5mm,易与蒙皮共形,能够同时满足L频段多种数据链功能和C频段无线电测高功能需求,可广泛应用于航空航天领域。     

互耦效应对泰勒阵列天线的影响分析

互耦效应是低副瓣阵列天线分析与设计中需要考虑的重要问题.在经典阵列综合方法--泰勒综合法的基础之上,仿真分析了互耦效应对方向图副瓣性能的影响.结果表明,互耦效应对阵列天线的低副瓣性能影响较为严重.     

移动电视智能天线自适应算法综述

首先介绍了智能天线的基本概念和分类,随后着重介绍了三种自适应算法。继而描述了将智能天线用于车载高清晰数字电视的研究,最后提出了智能天线有待研究的课题。     

新型宽带天线阵列

(2012-326-英国-195)曼切斯特大学发明的一种新颖、成本低、重量轻、极宽带阵列天线具有双偏振能力的天线阵列。该天线阵列的频率比>3:1,使其应用范围可以扩展到更多领域。它可以作为一个可操纵的阵列(发送,接收或两者),并具有低的交叉极化水平。同时它也可以进行多种传输服务。该天线应用领域包括移动/海洋通信,国防/安全,雷达成像,医疗保健监测等。     

煤矿井巷自适应多天线理论与关键技术研究

在分析煤矿井巷无线信号传播环境特点及多天线辐射特性的基础上,提出了融合巷道波导理论和自适应阵列天线相关技术的自适应多天线技术,介绍了煤矿井巷自适应多天线的基本组成和原理,并探讨了其需进一步研究的关键技术。煤矿井巷自适应多天线可根据信道传输特征有选择地控制导引波模的数量、类型和强度,从源头上改善井下无线通信覆盖状况,提高煤矿无线通信系统性能。     

基于遗传算法的低副瓣阵列天线综合

为得到更低副瓣的方向图,建立16单元线天线阵和32×32单元面天线阵遗传算法模型,并对这两类阵列天线方向图进行综合。将综合仿真结果与Chebyshev、Taylor两种传统综合方法进行比较。比较结果表明,遗传算法优化方向图的第1副瓣电平可达-40dB,且优化效率比传统方法高很多。为遗传算法在阵列天线方向图综合中的应用提供了技术支持。     

基于压缩感知技术的自适应阵列天线滤波系统的研究

随着通信等行业的发展,对自适应阵列天线滤波系统的吞吐量提出了更高的要求。本文利用压缩感知技术的稀疏化特点降低数据的计算复杂度。首先减少天线阵元所接收信号的测量数据,再送至自适应天线系统进行滤波处理,然后通过重构算法——SP算法(子空间匹配追踪)进行信号重构,能有效地降低自适应阵列天线滤波系统的计算复杂度,提高自适应阵列天线滤波系统的数据吞吐量。     

多载波CDMA系统的残留频率偏移估计及补偿方法*

结合多载波CDMA的系统模型,考虑了由于多径传输而产生的多普勒频移对接收端不同子载波存在不同频偏的影响;分析了残留频率偏移对接收信号产生的影响,利用在频域内插入导频、分块估计接收端信号的残留频率偏移,并在时域内进行补偿,最后给出了仿真结果.     

一种低复杂度的载波偏移估计算法

针对载波偏移引起OFDM系统的严重子载波干扰和性能下降这一问题,提出一种在承载数据子载波中间插入不承载数据的子载波的算法,算法是通过从时域OFDM符号的前半部分和后半部分的相位差获取频率偏移的信息来估计频偏的。这种算法不仅计算复杂度较低,而且估计准确,在多径信道条件下频偏校正后系统的性能能基本接近信道理想估计条件下的误比特率。     

一种用于OFDM时域频偏估计的频偏取值判决机制

提出了一种可适用于OFDM时域频偏估计的频偏取值判决机制,根据两个自相关峰值估算出大范围频偏粗值和小范围频偏粗值,由频偏取值控制状态器根据大范围频偏粗值和小范围频偏粗值的数值逻辑关系,确定频偏取值状态,由频偏取值执行器根据频偏取值状态计算准确的最终频偏数值。经802.11n接收机系统的频偏仿真测试表明,在IEEE TGN多径信道A~信道F条件下,其频偏估计均方误差<10-2误差(SNR>5),估算范围达正负2.5倍子载波频率间隔。     

Microstrip patch antenna feed for offset reflector antenna for dual band application

In this article, details of a dual band microstrip patch antenna (MPA) array feed for an offset reflector antenna is presented. The main objective of the proposed structure is to achieve low cross‐polarization at Φ = 90° plane in the reflector pattern. Low cross‐polar levels in the reflector pattern are achieved by illuminating the reflector with fields of the proposed dual band feed structure. A centered circular array as the dual band feed structure is proposed in which the central radiating element is a dual mode circular MPA operating at 6 GHz and the surrounding circular ring of eight circular MPA elements operating at 4 GHz in the dominant mode. The dual mode central antenna uses the concept of conjugate field matching for cross‐polarization reduction. TM₂₁ mode is excited at an appropriate ratio with the TM₁₁ mode to achieve the proper field matching at 6 GHz. The radius of the surrounding circular array is varied to obtain cross‐polarization better than ?30 dB at both the resonant frequencies. The offset reflector gain is found to be better than 37 dB with a 2.5 m parabolic reflector and F/D = 0.8 at both the operating frequencies.     

Investigation of factors contributing depolarization in offset reflector antenna and trimmed‐reflector offset parabolic antenna with lower cross‐polarization

This article outlines impact of various factors on cross‐polarization characteristics of offset reflector antenna for communication spacecraft with smaller sized bus at C band. Effects of different parameters are considered in rigorous analysis of the antenna. Measured and predicted performances are found in agreement. To fulfill specific requirement of higher edge‐of‐coverage gain (>26 dBi) and higher cross‐polarization discrimination (XPD > 30 dB) over a wider coverage and dual linear polarization under the imposed constraints, a novel trimmed‐reflector offset parabolic antenna (TROPA) is devised. This interesting configuration is obtained by trimming both sides parallel to symmetrical plane of a parabolic offset reflector antenna. Parametric study of trimming distance versus its impact on cross‐polarization is also presented. The TROPA acquires wider bandwidth, simplification in its mechanical design and manufacturing, and offers low weight and compactness. It is also shown that trimmed reflector has almost even RF performance in presence of spacecraft body and other antenna. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2012.     

一种高增益宽频带圆极化微带阵列天线的研制

针对微带天线阻抗匹配带宽一般较窄的自身缺陷,基于相控阵雷达天线的应用背景,设计了一种工作在X波段的双层圆极化微带天线结构,且优化发现,其各电磁参数良好。为提高其增益,还在此基础上设计并最终制作了双层2×2结构的微带天线阵列,其实测性能与设计值相符,增益达到10.7dB,带宽1.2GHz,相应轴比为4dB,符合圆极化要求。     

MB-OFDM UWB系统频偏估计方法改进研究

针对多带OFDM超宽带(MB-OFDM UWB)系统,依据物理层国际标准ECMA-368,对现有的频偏估计方法做了改进,提出了一种高性能、低复杂度、高鲁棒性的联合载波和采样频偏估计方法。该方法在SC算法基础上,通过选择合适的相关距离,使频偏估计算法适合于所有的跳频模式,同时也改善了估计性能。仿真结果表明,新方法在保证估计性能的基础上可有效降低复杂度,适合于高速MB-OFDM UWB系统。     

一种阵列天线通道不一致性的校正算法

基于对3G通信网络中阵列天线通道不一致性校正算法的性能分析,提出了一种基于参考信号源的自适应阵列天线通道不一致性校正算法。该算法充分利用了B.Friedlander算法和注入参考信号的校正方法的优点,通过使用参考信号的到达角估计值信息,来自适应地校正阵列天线中各阵元参数的不一致性,这些参数包括增益、幅度和相位因子。计算机仿真实验表明,推荐的算法大大改善了MUSIC算法估计来波信号方向的准确性,其性能远远超过了已有的各种校正算法。     

A versatile pattern synthesis algorithm for circular antenna array

This article presents a versatile pattern synthesis algorithm for controlling the sidelobe level and nulling region for circular antenna arrays. Nonuniform fast Fourier transform using the min–max interpolation method is utilized to overcome the nonlinear feature of circular arrays. The major advantage of the proposed algorithm is low complexity, which is key for hardware implementation. Moreover, the proposed algorithm functions well in amplitude‐only pattern synthesis, which may be required for low‐cost array systems using attenuators instead of complete amplitude and phase adjustment modules. Additionally, element failure of antenna arrays can be minimized in practical operations by resynthesizing the pattern by using the remaining antennas to achieve satisfactory performance. Simulation results indicate the lower complexity and higher versatility of the proposed algorithm compared with the conventional methods.     

A compact dual frequency microstrip antenna

In this study, we present a new technique for the development of a dual frequency microstrip antenna. Two identical polarizations at two far apart frequencies have been generated in a compact configuration which uses two elements fed by a single feed line. This design technique provides an independent control to the desired frequencies and reduces element size by 50% compared to the conventional design at the cost of a marginal decrease in gain. The proposed antenna produces dual resonances at 4.056 and 4.96 GHz. It yields impedance bandwidths of about 1.71% at the lower resonance and 1.41% at the higher resonance respectively. It exhibits 7.0 and 6.6 dBi gains at the lower and upper resonances respectively which are 0.3 and 0.7 dB lower than a conventional patch. The measured cross polar discriminations of the proposed antenna are also comparable to the conventional patch. The measured efficiencies are 81.3% and 78.1% respectively.