地球单基ISAR对月球成像信号参数设计与仿真

利用地基逆合成孔径雷达（Inverse Synthetic Aperture Radar,ISAR）对月球进行观测和成像处理,可获得月球正面的地形地貌等特征。本文首先构建了用于逆合成孔径雷达成像的地面单基雷达对月球观测的等效转台模型,分析了月球表面等效散射中心与雷达径向距离的变化特性。然后,给出了单基雷达脉冲重复频率、脉冲宽度、工作频段、带宽和采样频率等信号参数的设计准则,并建立了单基雷达对月球观测的ISAR回波模型与成像处理流程。最后,通过仿真实验验证了本文理论分析和成像算法的有效性。     

FMM结合改进自适应MBPE技术快速求解单站RCS

电大目标单站RCS的计算效率已成为积分方程法求解电磁散射问题的关键技术之一.为了快速而准确求解,对已有自适应采样算法进行了改进,不仅适合并行计算,而且提高了搜索效率.最后,将基于改进自适应采样算法的Pade有理逼近与采用快速多极子加速方法的MoM结合求解几个典型实例的单站RCS,数值结果表明了该方法的有效性.     

粗糙金属表面的高频太赫兹散射特性

以五种不同粗糙度金属圆盘作为目标体,在收发同置雷达体制下开展了频率为3.11 THz太赫兹波的散射特性的测试工作。实验表明:粗糙金属表面对太赫兹波的散射与入射波的频率、目标的材质、表面的粗糙度等多种因素有关,同时在收发同置体制下散射强度随散射角衰减迅速,当散射角超过18°后几乎全部衰减为0,实验中散射角度与散射强度之间的散射模式遵从一种指数关系。     

不规则海域收发合置混响强度建模与验证

＂不规则海域＂是水平边界和海底边界形状不规则的海域。从边界混响产生的物理机理出发,以射线声学为基础,用Lambert散射定律计算海底和侧壁面的散射,建立浅海不规则海域混响强度模型。该模型仿真计算出的收发合置平均混响强度与实验数据测得的混响强度相符。该混响强度模型能准确地计算此类海域的平均混响强度。     

水声多径单阵元主动时间反转检测性能研究

利用时间反转(Time Reversal,TR)良好的环境宽容性以及能量聚焦性,单阵元收发合置换能器通过主动时反信号对低信噪比下目标进行检测,以经典射线理论建立海洋中声多径信道传播模型,基于理论推导了单阵元主动TR信号目标检测的可行性.从理论上对单阵元收发合置换能器主动TR的处理增益进行详细分析,推导出单阵元主动TR的...     

太赫兹雷达散射截面测量中定标体的确定

围绕赫兹雷达散射截面定标体选定的内容开展了一系列工作,确定了适合作为太赫兹雷达散射截面标准体的工艺要求和加工方式,并先后对6种通过不同工艺加工成的太赫兹雷达散射截面的标准体材料进行了测试,分别测出半球反射率随波长的变化关系,确定了适合作为太赫兹雷达散射截面标准体的工艺要求和加工方式,加工出符合条件的太赫兹雷达散射截面测量中用作定标金属铝球,并利用该定标体对其他目标体在低频太赫兹波段的雷达散射截面进行了初步测量。     

High isolation,proximity‐fed monostatic patch antennas with integrated self‐interference cancellation‐taps for ISM band full duplex applications

This work presents two dual polarized proximity‐fed monostatic patch antennas with improved interport isolation for 2.4 GHz industrial, scientific and medical band same frequency full duplex wireless applications. The presented antennas achieves the high interport decoupling through intrinsic isolation of the polarization diversity in conjunction with a simple single‐tap and two‐taps self‐interference cancellation (SIC) topologies. The polarization diversity isolation is achieved through two perpendicular microstrip feeds for proximity feeding to excite orthogonal polarization mode for transmit (T_x) and receive (R_x) modes. The prototype for proposed antenna with integrated single‐tap and two‐taps SIC circuit is tested to record its interport isolation, impedance bandwidths and gains for both T_x and R_x ports. The implemented antenna with single‐tap SIC circuit demonstrates 10 dB return‐loss bandwidth of ≥100 MHz for both T_x and R_x ports. The measured isolation exceeds 40 dB over the 40 MHz bandwidth. Moreover, the recorded peak isolation is better than 74 dB for implemented antenna prototype. Furthermore, the 40 MHz bandwidth with 40 dB isolation can be tuned with the help of SIC‐tap as demonstrated through the experimental results. The measured gain levels are around 4.6 dBi for both T_x and R_x port. The same antenna structure with integrated two‐taps SIC topology features better than 55 dB isolation within 10 dB return loss bandwidth of 100 MHz. The peak isolation exceeds 97 dB and isolation levels are better than 60 and 80 dB over 50 and 20 MHz bandwidths, respectively, for presented antenna with two‐taps SIC configuration. The compact antenna offers comparatively wider impedance and isolation bandwidth with improved SIC levels compared to previous designs.     

固定单基地被动声纳目标航向估计方法研究

针对匀速直线运动的目标,依据相对运动三角形,利用任意不同时刻的3个方位值计算得到目标初始舷角,进而求取目标航向;基于一元线性回归分析理论,充分利用所测目标时间方位序列,构造系统函数,依此提出一种精度较高的目标航向估计算法;分析了不同运动态势下,观测数据的时间长度和方位精度对估计结果的影响。仿真结果表明,提出的算法精度较高,在观测方位误差相对较大时也同样适用,且随着观测数据时长增加、方位变化率增大以及观测方位精度增高,目标航向的估计结果越稳定。     

A RD-ESPRIT algorithm for coherent DOA estimation in monostatic MIMO radar using a single pulse

This paper discusses the problem of coherent direction of arrival (DOA) estimation in a monostatic multi-input multi-output (MIMO) radar using a single pulse, and proposes a reduced dimension (RD)-estimation of signal parameters via rotational invariance techniques (ESPRIT) algorithm. We reconstruct the received data and then utilise it to construct a set of Toeplitz matrices. After that, we use RD-ESPRIT to obtain the DOAs of the sources. The proposed algorithm is effective for coherent angle estimation based on a single pulse, and it has much better angle estimation performance than the forward backward spatial smoothing (FBSS)-ESPRIT algorithm and the ESPRIT-like of Li, as well as very close angle estimation performance to the ESPRIT-like of Han. For complexity comparison, our algorithm has very close complexity to the FBSS-ESPRIT algorithm, and lower complexity than the ESPRIT-like of Han and the ESPRIT-like of Li. Simulation results present the effectiveness and improvement of our approach.     

基于Kirchhoff近似法的目标声散射场仿真

对经典的Kirchhoff公式作一定的假设,得到收发合置情况下的近似Kirchhoff公式,进一步对球体目标声散射场进行求解。在MATLAB平台下,仿真出目标声散射场的相关曲线,并对声散射场与作用距离和入射波频率的关系进行了对比分析。应用表明,结论对于水下掩埋目标探测与识别的研究具有一定实用价值。