毫米波合成孔径雷达的发展及其应用

分析了毫米波SAR高分辨成像的基本原理,阐述了毫米波SAR的优点,并结合目前国际上典型的毫米波SAR系统,综述了毫米波SAR技术与系统的发展状况,讨论了毫米波SAR的应用前景、存在的问题以及未来的发展趋势.     

目标三维转动对弹载毫米波SAR成像分析

在弹载毫米波SAR对地面运动目标的成像过程中 ,目标往往存在三维转动 ,即偏航 (yaw)、俯仰 (pitch)和横滚 (roll) ,使得目标回波的多普勒频移是时变的 ,全过程的多普勒频谱不能真实反映散射中心的横向分布。本文在建立了目标角运动模型的基础上 ,详细分析了回波信号的多普勒频移 ,最后通过仿真结果说明了机动目标的三维转动对弹载毫米波SAR成像质量的影响     

基于MLBF的毫米波双站SAR前视Omega-k成像算法

结合毫米波体制和双站毫米波合成孔径雷达(SAR)前视成像技术,开展毫米波双站SAR前视成像算法的研究.在双站SAR前视成像系统中,较大的前视角引入了多普勒质心偏移和严重的距离徙动,因此普通双站SAR的成像算法无法直接移植到双站SAR前视成像中.针对以上问题,论文首先提出了一种基于瞬时多普勒分析的改进Loffeld's Bistatic Formula(MLBF)二维频谱求解方法,相比于现有方法,该方法能更准确的得到双站SAR前视回波信号的二维频谱.在此基础上又推导出了适用于毫米波双站SAR前视成像的Omega-k算法;最后通过仿真实验,验证了提出算法的有效性和优越性.     

基于导航数据的Ka 波段InSAR 成像处理与分析

与其它波段相比,毫米波干涉SAR (InSAR)具有精度高、体积小的特点,是目前干涉SAR 研究的重要方向之一。但由于较短的波长,其也给成像处理和干涉相位提取带来了一定困难。该文利用毫米波段干涉SAR 数据,采用流结构后向投影(BP)算法结合IMU 进行了毫米波SAR 成像和干涉相位分析。研究发现,由于毫米波波长短,对天线相位中心变化更为敏感,为了保证系统的干涉相位,必须利用IMU 数据进行精确的运动误差补偿。通过实测数据验证了采用各自计算天线相位中心的策略,后向投影算法可以在成像过程中精确补偿平地相位。      

Ka波段宽频带频率选择表面设计

随着毫米波技术的发展和毫米波天线的广泛应用,提出了对毫米波雷达隐身的要求。基于耦合和谐振原理,设计了一种Ka波段带内透过的单层频率选择天线罩。利用谱域法对频选天线罩进行了分析计算。优化得到的天线罩仿真结果在Ka全波段内平均插入损耗小于1 dB,在45毅扫描角内35 GHz的S21 >-1. 7 dB,实现X 波段和Ku波段内的透过率小于-11 dB。最后,对频选罩的相关参数特性进行了分析,便于针对其他电性能要求进行优化改进。     

车载毫米波SAR对近海域的成像及监测

针对近海域监测的应用背景,介绍了一种用于近海监测的车载毫米波SAR系统,该系统灵活机动、费用低廉,结合了毫米波和SAR的特点,能够实砚对近岸静止扣活动目标的高分辨成像及监测。在此对某次实验获得的SAR数据进行了成像处理,由于在系统要求的作用距离范围内,距离单元数不是很多,可对每个距离单元都构造一个方位匹配函数,保证方位向的高分辨率不受损失,为海面舰船目标的检测研究提供高分辨SAR图像。     

低耗低剖面单层波导阵列天线研究

新型单层波导阵列天线具有低耗、低剖面、结构紧凑、实用性强等诸多优点, 在毫米波甚至太赫兹无线通信领域具有巨大应用潜力, 是当前的研究热点。 文章首先介绍了用于构建波导阵列天线的几类波导馈电网络的特点, 指出E 面波导馈电网络在毫米波应用领域的优势,接着针对E 面波导在单层并馈波导阵列天线和Butler矩阵多波束阵列天线方面的研究展开叙述,最后给出了可应用在单层波导阵列天线中的开口波导辐射单元在实现多频和圆极化等不同功能上的最新研究进展。 文章对于低耗低剖面单层波导阵列天线的发展及其应用具有参考价值。     

无线电电子学的应用

TN99 02041832毫米波辐射对K562细胞作用机制研究/方昆阳,赖声礼,罗绍凯,王霄(华南理工大学)∥华南理工大学学报。-2001,29(12).-6-9观察了毫米波辐射对K562细胞超微结构、钙离子沉淀分布和线粒体跨膜电位(△ψm)变化的影响,发现低功率密度的毫米波辐射可以引起多数细胞的细胞膜形态立即发生变化,同时引起内质网池极度扩张,边缘钙离子沉淀增多,辐射结束数小时内凋亡细胞逐步增多。表明低功率密度的毫米波辐射通过影响细胞膜和内质网,引起胞内钙离子浓度升高从而诱导细胞凋亡。图8表1参4(木)TN99,TP319 02041833水情遥测系统中快速差错校验的软件方法/茅志兵,孙玉龙,孙典红(河     

车载毫米波高分辨实时SAR系统对江中船只识别的方法

随着社会的发展,江河中的船只种类越来越繁多,一些船只不按规定的时间和航线胡乱行驶,这给管理工作造成了极大地不便.本文提出了一种采用实时的毫米波高分辨SAR系统进行河流湖泊船只识别的方法,通过对SAR 成像算法、目标识别、ISAR成像跟踪等的分析论证了高分辨SAR实时成像、跟踪系统的可实现性.从而构建成车载毫米波高分辨SAR系统,通过对河流船只进行实际的成像、目标识别、跟踪实验,验证了此系统可以全天候的对河流湖泊中的船只种类进行实时识别并进行跟踪,从而方便管控.     

《电讯技术》专题资料《近空间飞行器测控与信息传输技术》题要（三）

基于平流层飞艇的毫米波SAR雷达系统（何均,任培宏）近空间平台雷达系统具有广阔的应用前景,本文针对平流层飞艇这一近空间平台,米波雷分析了毫米波SAR雷达的特点、系统组成、相关指标及关键技术等,初步探讨了毫达在近空间平台应用的可行性。     

Analysis of Millimeter Wave Power Density Received by Cell Monolayers Inside Culture Dishes

One sort of experiment concerning biological effects of millimeter waves (MMWs) at the cellular level is performed using a culture dish containing a cell monolayer with MMW irradiated from the underneath. For culture dishes with diameters much larger than the wavelength, analysis is carried out with respect to the relationship between the portion of the incident MMW power density (PD) received by the cell monolayer and influencing factors such as the culture dish bottom thickness, MMW wavelength, and the electromagnetic properties of the dish and culture solution. Another analysis is conducted by the FDTD method to reveal the effect of culture dish configuration on MMW PD received by the cell monolayer in a typical culture dish with a diameter not much longer than the wavelength. With the illustrated results, the conclusion is reached that rigorous analysis, precise measurement and accurate calculation of MMW PD should accompany such experiments, and large-diameter culture dishes are more preferred in experiments to small-caliber dishes.     

Algorithm Analysis on MMW Dosimetry for the Cell Monolayer Cultered in Petri Dish with the FDTD Method

Four algorithms are developed to help the dosimetry study for experiments on millimeter-wave (MMW) biological effects on cells in vitro with the finite-difference time-domain (FDTD) method. Their performances in evaluating the MMW irradiation dose are displayed and compared, including the induced current density and the specific absorption rate (SAR), that are distributed over the cell monolayer cultured in Petri dish. With the discussion on individual characteristics of the algorithms, the conclusion is reached that an appropriate algorithm is essential in providing accurate data on the MMW irradiation dose by way of numerical calculation, which should be considered carefully in related experiments.     

A coplanar-waveguide system for cells exposure during electrophysiological recordings

In order to investigate the biological effects of microwave electromagnetic (EM) fields as those emitted from mobile telecommunication equipment, a suitable exposure system has been designed. The system is specific for real-time acquisition of membrane ionic currents in a biological cell, i.e., patch-clamp recordings. Both numerical and experimental characterizations are considered, in terms of EM field and specific absorption rate (SAR) distribution in the Petri dish containing the biological target. Results show a good efficiency of the system in terms of SAR induced in the sample by incident input power.     

Wi-Fi对成骨细胞ROS的影响

通过对近距离（3 cm）暴露于2.45 GHz Wi-Fi射频辐射的MC3TC-E1细胞的比吸收率（specific absorption rate,SAR）和温度变化进行时域有限差分（finite-difference time-domain,FDTD）法仿真,检测细胞活性氧（reactive oxygen species,ROS）,探索体外培养的成骨细胞对2.45 GHz射频辐射能量的吸收和升温效应,及其非热效应对ROS的影响.研究结果表明:输出功率为500 mW 2.45 GHz Wi-Fi辐射90 min可使细胞平均温度升高0.5℃,升温最高点小于1℃;细胞培养皿总平均SAR值为0.835 6 W/kg,最大值为1.259 4 W/kg,最小值为0.553 7 W/kg;90 min 2.45 GHz Wi-Fi射频能量的非热效应可引起成骨细胞ROS的升高,ROS和SAR值正相关,Wi-Fi长时间辐射会影响骨的代谢.     

SAR EVALUATION IN THE 0.25 MM HUMAN EYE MODEL EXPOSED TO 30 GHz MILLIMETER WAVE

We have evaluated the specific absorption rate (SAR) in the eye induced by the perpendicular incidence of 30 GHz uniform plane millimeter wave (MMW). An anatomically based 0.25 mm voxel model of the eye with 10 types of tissue is constructed. Debye’s dispersion equation is used to derive the dielectric properties of the eye tissues and biological materials in the neighboring region. The three-dimensional (3-D) finite-difference time-domain (FDTD) algorithm and the perfectly matched layer (PML) absorbing boundary conditions are used in the numerical simulation. The FDTD code is validated against the Mie theory. The SAR deposition in the eye is calculated and displayed, with the analysis on the SAR distribution characteristics. The average SAR values in the cornea, the lens cortex, the lens nucleus, the humor, and the whole eye are statistically derived and examined against present irradiation safety standard.     

ANALYSIS OF WAVEFORM ERRORS IN MILLIMETER-WAVE LFMCW SYNTHETIC APERTURE RADAR

In remote sensing applications, there is a special interest in the lightweight, cost effective, and high resolution imaging sensors. The combination of linearly frequency modulated continuous wave (LFMCW) technology and synthetic aperture radar (SAR) technique can lead to such a sensor. This paper concentrates on the analysis of waveform errors in millimeter-wave (MMW) LFMCW SAR. The generating scheme of millimeter-wave LFMCW waveforms with phase locked loop (PLL) and direct digital synthesizer (DDS) combined frequency synthesizer is investigated. The impacts of quantization errors, spurs, and frequency nonlinearities are analyzed. Simulation results show that the quality of LFMCW waveforms has a direct influence on the SAR images. Hence a scheme of frequency synthesizer to achieve high performance MMW LFMCW waveform is proposed. This synthesizer driven by a DDS array can adaptive suppress the spurious level without degradation of excellent frequency linearity and fast switching speed.     

Compressed Sensing for Millimeter-wave Ground Based SAR/ISAR Imaging

Millimeter-wave (MMW) ground based (GB) synthetic aperture radar (SAR) and inverse SAR (ISAR) imaging are the powerful tools for the detection of foreign object debris (FOD) and concealed objects that requires wide bandwidths and highly frequent samplings in both slow-time and fast-time domains according to Shannon/Nyquist sampling theorem. However, thanks to the compressive sensing (CS) theory GB-SAR/ISAR data can be reconstructed by much fewer random samples than the Nyquist rate. In this paper, the impact of both random frequency sampling and random spatial domain data collection of a SAR/ISAR sensor on reconstruction quality of a scene of interest was studied. To investigate the feasibility of using proposed CS framework, different experiments for various FOD-like and concealed object-like targets were carried out at the Ka and W band frequencies of the MMW. The robustness and effectiveness of the recommend CS-based reconstruction configurations were verified through a comparison among each other by using integrated side lobe ratios (ISLR) of the images.     

Experimental and numerical determination of SAR distributions within culture flasks in a dielectric loaded radial transmission line

The effect of dielectric loading on the cell layer specific absorption rate (SAR) within a T-75 culture flask being irradiated within a transverse electromagnetic (TEM) cell was studied both experimentally and numerically. Direct thermal measurements of a T-75 containing 40 mL of culture medium and resting upon a 3-mm-thick slab of alumina ceramic (epsilon r = 9.6) revealed that, compared to the same flask resting upon a foam slab (epsilon r = 1.0) of the same thickness, the average SAR at the cell layer was increased roughly fourfold. This fourfold increase is significant experimentally because it allows biologists to perform experiments over a larger range of SAR values needed to determine possible dose-response curves without the costs and difficulties of a fourfold increase in amplifier power. Finite-difference time-domain (FDTD) simulations of the SAR distribution were in good quantitative agreement with the experimental measurements. It is concluded that FDTD modeling can be a cost effective and scientifically acceptable means of obviating the thermal measurement of SAR.