浅谈UWB超宽带无线通信技术

本文对UWB超宽带无线通信技术的基本原理、工作机制以及相关标准进行了描述,着重分析了UWB技术所独具的特点,并与IEEE802.11a、蓝牙、HomeRF等短距离无线通信技术进行了比较。     

利用等效模型分析倒F天线

在传统微带天线的传输线模型和腔模法模型的基础上，提出了分析倒F天线的传输线模型和腔模法模型，并利用这两种模型对倒F天线进行了理论分析.将计算结果与IE3D的模拟结果进行了比较，从而证明了该文方法的有效性.     

双H型比相测向天线的测向精度研究

本文简述了通信对抗中用来精确、快速测定无线电电台方位的测向天线的原理，建立了双Ｈ型比相测向天线的相位方向性函数和幅度方向性函数，用数值计算分析了天线之间的互耦与测向精度的关系；理论结果为实验数据提供了理论依据，同时也找到了提高测向精度的途径，在研制此类天线中有其参考价值．     

基于信干噪比增益的自适应阵列抗干扰性能分析

针对自适应阵列现有的抗干扰性能评价指标存在权系数伸缩敏感,难以直观反映后续信号处理性能等缺点,在现有性能指标分析基础上,提出了信干噪比(SINR)增益指标,并给出了均匀线性阵列SINR增益的解析表达式. 新指标具有明确物理含义,可方便比较不同空域滤波器的抗干扰性能,并定量反映抗干扰后续的信号处理性能. 仿真实验结果验证了提出新方法的有效性.      

非视距环境下超宽带信号多重绕射仿真研究

利用时域一致性绕射理论(UTD)和物理光学(PO)的方法来仿真非视距环境下超宽带(UWB)信号多重绕射传播特性.由于该方法利用一组简单的递推关系来代替一致性绕射理论中复杂的斜率绕射项,从而提供了一种简化的基于时域一致性绕射理论的多重绕射分析方法.利用上述方法推导了著名的Bertoni模型的时域冲激响应,利用卷积运算可以简便地预测仿真环境下接收点的超宽带信号.数值结果表明,这种基于时域UTD-PO的分析方法不仅能够用来准确地分析多重绕射模型而且还能够明显节省运算时间;相比楔形障碍物,圆形障碍物对接收点波形的影响较小.     

基于DS-UWB超宽带系统中小波去噪计算机仿真

超宽带系统信号脉冲持续时间极短，功率谱密度极低，传统去噪方法不能满足要求，在超宽带系统中使用小波变换模极大值法抑制噪声效果比较理想，它既能有效抑制噪声，又能保留UWB信号的奇畀性。仿真结果表明该方案算法简便、效果明显。     

Signal processing method of a novel polarized array radar seeker

This paper proposes a novel polarized radar seeker based on the polarized antenna array. A fully polarized signal processing method for the proposed radar seeker is studied under the environments with electromagnetic interferences. A dual polarized antenna array is employed to transmit and receive the radar signals. The instantaneous polarization signal processing technique is used to detect and recognize the targets. The direction of arrival （DOA） of the target is measured through the spatial spectrum with high resolution for the polarized array radar seeker system. The fully polarized signal model of the polarized array radar seeker is formulated and a specific signal processing algorithm is expounded. The theoretical research and numerical simulation results demonstrate that the proposed radar seeker has good performances in target detection and electronic warfare. The research results can provide an effective technical approach to develop and research the new generation radar seeker.     

Direction of arrival estimation on cylindrical conformal array using RARE

When the information of mutual coupling and shadowing effect of a conformal antenna array are unknown,the performance of direction of arrival (DOA) estimation will be seriously degraded by using some classical methods,such as the multiple signal classification (MUSIC) algorithm.Meanwhile it is difficult to measure or estimate the shadowing effect.The DOA estimation for a conformal uniform circular array (UCA) is studied.Firstly,the azimuthal angle is separated from all the unknown information by transforming the UCA from the element space to the mode space.Then the rank reduction (RARE) algorithm is applied in the estimation of the azimuthal angle.The π ambiguity existed in the RARE is solved by the beam forming.The main advantage of this method is that it does not need to measure the mutual coupling and the shadowing effect.Compared with the subarray method,it will not decrease the aperture of the array.Simulation results validate the advantages of the method.     

高速运动环境下GNSS接收机阵列抗干扰算法

全球卫星导航系统(global navigation satellite system, GNSS)接收机高速运动状态下,干扰信号来向快速变化将导致阵列抗干扰算法性能下降,为此提出了基于干扰加噪声协方差(interference-plus-noise covariance, INC)矩阵重构的零陷加宽算法。首先,依据采样协方差矩阵相邻特征值之比估算干扰信号数目。然后,利用空间谱估计值粗略判定干扰信号来向,并根据零陷展宽需求重新设定干扰区域空间谱估计值。最后,以干扰区域谱估计值为基础重构INC矩阵,求解阵列权矢量。仿真实验表明,相比于其他零陷加宽算法,所提算法在相同展宽下的零陷更深,阵列输出载噪比(carrier to noise ratio, C/N₀)也高出5 dBHz以上。     

基于导电织物的柔性可拉伸天线设计

基于柔性导电织物设计一种工作于2.45 GHz的柔性可拉伸天线, 并研究不同拉伸应变对柔性织物天线性能的影响规律及辐射特性. 仿真及实测结果表明, 在中心频率2.45 GHz处, 回波损耗的仿真与实测值分别为-40,-26 dB, 仿真与实测增益方向图在中心频率处一致性良好.