主瓣干扰极化抑制的新方法

提出了一种针对主瓣压制干扰的空域虚拟多通道并行极化滤波技术.利用天线在空域扫描时的极化慢变特性,对接收到的干扰信号进行处理,获得正交极化回波与极化状态的估计,然后以最佳极化进行极化滤波,以达到抑制噪声干扰的目的.通过采取并行处理,该方法能够消除仰角估计误差对抑制性能的影响.理论分析和仿真表明,该方法可使单极化雷达具备极化信息处理能力,进而获得较大的性能提升.     

星载合成孔径雷达双极化天线阵研究

介绍了一种宽带双极化星载SAR有源相控阵天线阵,该天线以TR组件和双极化线阵组成的有源线阵为基础,并根据相控阵天线对雷达信号瞬时带宽的限制条件,选择合适的实时延迟子阵,结合结构安装的要求,构成电气独立的模块。在此基础上,根据雷达对天线孔径大小的需要,通过馈电网络激励拓展成大型有源相控阵天线,该天线可以通过波控灵活的控制和网络的合成,实现多极化、波束扫描、波束赋形和多通道等功能。其中对于双极化辐射天线,分别针对微带贴片天线阵和波导缝隙天线进行了分析和研究,并给出了实验验证结果。微带天线阵采用宽带的双层贴片辐射单元和并馈网络实现大带宽要求,两种正交极化模式分别由共面微带线和缝隙耦合来激励,其馈电网络居于开有耦合缝隙接地板的两侧,实现复杂网络空间安排和降低馈线耦合的功能。对于贴片单元的激励,采用对称、反相馈电和分组优化等方法,有效地提高了极化隔离度和极化纯度;而双极化波导缝隙阵中,以脊波导宽边纵缝谐振阵实现垂直极化,波导窄边非倾斜缝隙阵实现水平极化,在每种线阵中都通过分组馈电、过载技术和辐射/馈电波导一体化设计,实现了宽带和压缩横截面的目的。两种形式的天线阵比较,阵面剖面高度相当,微带阵具有宽带、轻质、易于加工和成本低等优势,而波导缝隙阵则具有高效、高隔离度和低交叉极化等性能,但是其缺点是结构复杂、加工难度大和重量大等。     

动态目标极化特性的仿真方法

研究对动态目标极化特性优化测试问题。针对动态目标极化特性存在连续变化难于实时识别问题,对雷达目标的航迹和姿态进行建模,采用了几类描述动态目标极化散射特性的特征参量,研究了目标运动对极化特性的调制影响,最后结合目标的运动轨迹,进行了动态目标极化特性测量的仿真,验证了仿真方法的正确性,得到的极化特征量,为目标分类识别系统提供了依据。     

基于极化合成的目标分类算法

极化合成是极化SAR图像处理的一种重要方法,它能在成像处理后,利用已获得的Sinclair矩阵重新生成任意极化方式下的雷达接收功率图像,并能通过选取收发天线极化状态相同或正交,分别得到描述目标散射特性的共极化特征图和交叉极化特征图。根据极化合成理论和极化特征图的概念,可以获取目标的最佳极化。将其作为分类器的输入特征量,提出了一种基于极化合成的目标分类算法,并对实测极化SAR数据进行了分类实验。结果表明,该算法对于从极化SAR数据中获取目标的最佳极化,进而对目标进行分类是可行和有效的。     

基于极化合成的目标分类算法

极化合成是极化SAR图像处理的一种重要方法，它能在成像处理后，利用已获得的Sinclair矩阵重新生成任意极化方式下的雷达接收功率图像，并能通过选取收发天线极化状态相同或正交，分别得到描述目标散射特性的共极化特征图和交叉极化特征图。根据极化合成理论和极化特征图的概念，可以获取目标的最佳极化。将其作为分类器的输入特征量，提出了一种基于极化合成的目标分类算法，并对实测极化SAR数据进行了分类实验。结果表明，该算法对于从极化SAR数据中获取目标的最佳极化，进而对目标进行分类是可行和有效的。     

基于双极化波激励的新型无芯片RFID标签设计

设计了一种新型高编码容量的无芯片射频识别(RFID)标签结构.标签由2组具有正交极化特性的"M"型缝隙谐振器构成,标签尺寸更加紧凑,雷达散射截面积(RCS)响应曲线具有更高的Q值.在±45°的2种极化的入射波激励下,通过极化复用及频移编码技术,标签在固定的超宽带频段内编码容量提高了6倍,在12 mm×18 mm的紧凑尺寸内实现24 bit的编码容量.     

雷达极化域调控超分辨的原理与方法

分辨是雷达领域的经典问题,尽管经过几十年的发展,但“分不开、辨不清”的矛盾在雷达各类应用中日益凸显.在雷达分辨研究中,模糊函数理论占据绝对主流,同时尝试突破瑞利(Rayleigh)分辨极限的超分辨研究层出不穷,这些方法具有一定的超分辨效果,但因其前提假设而在工程应用中受限.传统分辨理论并未考虑电磁场的极化特性,利用极化技术可大幅提升雷达分辨能力,研究极化与分辨的关系具有重大理论价值.本文从模糊函数出发,重点分析目标幅度和相位对分辨效果的影响,得出“等幅反相”可使雷达突破分辨率极限,结合雷达收发极化调控技术,创新性提出极化域变焦理论,通过全极化域距离像阐释超分辨原理,并且针对实际雷达系统,提出极化域变焦多目标检测与分辨方法,实现多目标的正确判决和距离的有效估计.仿真结果表明,极化域变焦处理对交叉极化不敏感,在高信噪比条件下可将雷达分辨力提升约20倍.     

极化MIMO雷达隐身目标检测性能研究*

多输入多输出(MIMO)雷达使用了远距分布的阵元,它利用了信号的空间分集增益来获取更多的目标信息。极化是另一种可以提高雷达系统性能的分集方式。当应对隐身目标时,传统的极化雷达在某些观测角度会遭受到较大的目标雷达截面积(RCS)衰减,而无法获得较好的检测性能。而在一个雷达系统中同时利用这两种分集增益,可以得到一种比传统极化雷达更具优势的新雷达检测系统——极化统计MIMO雷达,它可以更好地应对隐身目标检测。给出了相应的模型,并推导出了该雷达系统的检测性能解析式。将其与传统相控阵及非极化统计MIMO雷达比较,可以看到极化统计MIMO雷达的检测性能更佳。联系到隐身目标的特性,极化MIMO雷达的检测器特性应对它时具有显著优势。最后,以上方法通过仿真得到了验证。     

极化测量雷达的信号选择与处理

文中以模糊函数为基础,提出了一种新的极化测量雷达信号处理方法.该方法是传统极化测量雷达信号处理方法的扩展,它放宽了传统方法中对两路极化信号必须正交的严格要求,从而消除了传统方法中因为信号不能严格正交而产生的测量误差.基于该方法,文中提出了测量信号模糊函数矩阵这一概念,并利用模糊函数矩阵对常见的极化测量信号进行了归类和分析,模糊函数矩阵的提出为极化测量雷达的信号选择与设计提供了有力工具.最后,通过仿真实验验证了文中所提出的信号处理方法的优越性.值得指出的是,该信号处理方法不仅可用于分时极化测量体制雷达,也可用于瞬时极化测量体制雷达.     

基于四元数正交设计的三极化正交空时极分组码*

构建了一种四元数正交设计的三极化正交空时极分组码,该码满足正交设计关系,能够通过三极化天线进行发射和接收。在相同的系统条件下,对相同天线数的Alamouti码和双极化正交空时极分组码进行仿真比较,结果表明正交极化空时分组码在不增加空间体积和发射天线及接收天线数的情况下,可以有效降低误码率,提高系统性能。     

雷达最佳接收极化滤波优化研究

研究了雷达最佳接收极化滤波抗随机极化干扰的优化问题。当随机极化干扰的极化方式与目标回波的极化方式相近时,传统的最佳接收极化滤波方法在滤除干扰信号的同时,极大抑制了目标回波信号,导致信干噪比（SINR）降低。为解决传统最佳接收极化滤波存在的不足,提出收发联合极化滤波的优化方法。当目标回波和干扰有相近的极化方式时,通过对发射极化的捷变,改变目标回波信号的极化方式,从而避免目标信号的过度损失。与传统的滤波方法相比,该方法能获得更好的信干噪比。仿真结果表明了该滤波优化方法的可行性和有效性。     

A broadband radar cross section reduction metasurface based on integrated polarization conversion and scattering cancelation

In this paper, we proposed and demonstrated a broadband radar cross section (RCS) reduction metasurface by integrating polarization conversion and scattering cancelation. A broadband polarization conversion structure was designed based on split concentric ring. We used a 4 × 4 array of split ring structure and its mirror‐symmetric structure as the super‐cell units to construct a metasurface with chessboard structure. The metasurface can efficiently reduce the co‐polarization RCS for all azimuth angles of incident wave. The metasurface sample with optimized structure parameters was fabricated and measured. The measured 10 dB RCS reduction band of the metasurface is from 8.6 to 17.7 GHz.     

The signal selection and processing method for polarization measurement radar

Based on the ambiguity function, a novel signal processing method for the polarization measurement radar is developed. One advantage of this method is that the two orthogonal polarized signals do not have to be perpendicular to each other, which is required by traditional methods. The error due to the correlation of the two transmitting signals in the traditional method, can be reduced by this new approach. A concept called ambiguity function matrix (AFM) is introduced based on this method. AFM is a promisi...     

Transmitter polarization optimization with polarimetric MIMO radar for mainlobe interference suppression

Polarization diverse design of the transmit waveforms based on the property of the target scattering matrix provides better performance than transmitting waveforms with fixed polarizations, especially for mainlobe interference suppression applications. In this work, we propose a radar system combines the advantages of multiple-input–multiple-output (MIMO) systems with the advantages offered by optimally choosing the transmitter polarizations, in order to achieve a better mainlobe interference suppression performance. The polarization diversity is employed in the transmit array, while the receive array adopts 2-D vector sensors to measure the horizontal and vertical components of the received signal. The optimal transmitter polarizations can be obtained by maximizing the output signal-to-interference-plus-noise ratio (SINR) in each coherent processing interval (CPI). In addition, the discrimination method for the target and the interference is studied in this paper, along with the target scattering matrix estimation method. Simulation results demonstrate that interference can be effectively discriminated and suppressed with the radar configuration, and better interference suppression performance is achieved with the optimal transmitter polarizations.     

Wideband RCS reduction using polarization cancelation method

Polarization cancelation method to reduce the monostatic radar cross section (RCS) is investigated thoroughly. The inherent bandwidth of rotatable unit cells is determined. Also, 0‐dB RCS reduction bandwidth of any arbitrary method including polarization cancelation method is investigated. A special unit cell is proposed to reduce RCS over 100% fractional bandwidth. Finally, a structure is fabricated and measured so that results in verifying the performance of the proposed unit cell.     

Novel research on main-lobe jamming polarization suppression technology

A novel main-lobe blanketing interference suppression method which named as spatial virtual multiple channel concurrent polarization filter technology is proposed.It processes sample data using the slow varied polarization property of a scanning antenna.The orthogonal polarized signal and polarization states of the receiving signal can be obtained.The optimal polarization is then calculated for use in polarization filtering to achieve the objective of suppressing noise jamming.The effect of elevation measurement error on interference suppression performance is eliminated by concurrent processing.Theoretical and simulation results show that,this technology enabled self-polarization information processing for single polarized radar which improved its working performance.     

Polarization discrimination between repeater false-target and radar target

High fidelity repeater false-target badly affects a radar system’s detecting, tracking, and data processing. It is an available approach of confronting false-target for radar that discriminates firstly and then eliminates. Whereas for the technique progress about the repeater false-target jam, it is more and more difficult to discriminate this jam in the time-domain, frequency-domain, or space-domain. The technique using polarization information to discriminate the target and false-target is discussed in th...     

X波段标签式雷达反射器的设计

提出了一种用于雷达目标监测的新型标签式雷达反射器的设计方法,该方法在结构上采用在金属贴片上开L型缝隙的方式来增强其交叉极化响应。文章介绍了交叉极化项雷达散射截面的概念,给出了该类型标签式雷达反射器在全波电磁仿真软件(HFSS 13.0)上的散射特性和仿真结果。最后利用三维电磁仿真平台(FEKO 5.5)将最终形式的标签式雷达反射器阵列置于全尺寸的汽车模型前窗之上进行建模仿真,从而验证了其有效性和实用性。