基于U形槽和寄生条带的双陷波超宽带天线

针对超宽带系统易受窄带信号干扰的问题,提出了一种双陷波平面超宽带天线。通过在天线的辐射贴片上加载U形槽实现了5.1～5.9GHz频段内的陷波,在接地板上引入寄生条带实现了3.4～4GHz频段内的陷波。仿真与测试显示:该天线在3～11.1GHz的频带范围内具有良好的阻抗特性、辐射方向特性,在其中3.4～4GHz和5.1～5.9GHz范围内具有双陷波特性,与相关文献相比,能够有效地抑制WiMAX和WLAN系统之间的干扰,是一种性能较好、实用价值高、能广泛应用于超宽带系统中的陷波超宽带天线。     

基于开口环谐振器的小型化射频识别标签天线

为了克服标签天线小型化技术中结构复杂,不易于与标签芯片匹配等问题,设计了一种基于开口环谐振器(split ring resonator,SRR)的天线结构。为了实现天线与芯片之间的匹配,该天线采用T型馈电网络。仿真结果表明:该天线具有较好的S11特性。天线的工作频段也包含中国UHF频段的920～925 MHz。设计的天线尺寸约为30mm×25mm,结构简单,很好地实现了天线小型化,并用矢量网络分析仪对天线的阻抗特性进行测试,且测试结果与仿真结果基本吻合。     

弹载超宽带小型化阵列天线单元及阵列设计

通过天线单元中加载金属化过孔及馈电端采取三级阻抗变换等一系列手段设计一种Vivaldi天线单元,在5~11 GHz频段内驻波VSWR2,物理尺寸只有14 mm(宽度)×32 mm(高度)×1.07 mm(厚度),相比于传统Vivaldi天线,单元宽度尺寸减小了53%,并通过对辐射贴片边缘开槽降低了天线E面耦合,达到了超宽带小型化的设计结果。利用该单元设计了一个7×7的矩形阵列,该阵列全频带内扫描角度可达±60°,满足阵列天线设计要求,可应用于空空导弹弹载的超宽带相控阵天线中。     

平面正弦天线及其小型化馈电巴伦

研制一款工作频段为3～15GHz的两臂平面正弦天线，使用50Q同轴电缆馈电。正弦天线具有平衡辐射结构及超宽带特性，因此必须使用相应的馈电巴伦进行匹配转换。但传统的指数渐变微带巴伦纵向尺寸过大，通常为0．5λmax不利于整个天馈系统的紧凑布置。因此，设计了一种小型化的微带馈电巴伦并用于两臂平面正弦天线的馈电。通过测试比较发现，在其各项性能和常规微带馈电巴伦的正弦天线基本保持一致的前提下，纵向尺寸得到了很好的压缩，利于实现紧凑布置。     

三陷波特性的超宽带单极子天线

设计了一种具有三陷波特性的超宽带单极子天线。该天线通过在圆形贴片、馈线和接地板上引入半波长和四分之一波长的谐振电路,实现了三陷波功能,避免了与其他通信系统之间的干扰。通过仿真可知,天线的回波损耗带宽为1.88GHz～11.3GHz,陷波频段2.27GHz～2.60GHz,3.38GHz～4.12GHz和5.18GHz～5.93GHz,具有良好的辐射带宽和方向性。     

基于准行波阵的毫米波引信微带频扫天线

针对传统毫米波引信天线无法兼顾宽波束、高增益、小尺寸的问题,提出了一种基于准行波阵的毫米波引信微带频扫天线;该天线由5个微带贴片串联构成,天线尺寸仅为20 mm×8 mm,微带贴片之间距离固定,通过频率扫描方式改变天线主波束指向;毫米波引信在弹丸落地前根据落角信息计算出天线的主波束倾角,然后通过调整引信的工作频率使频扫天线主波束垂直照射到目标;仿真与实测结果显示:天线工作频率为30.2～35.6 GHz,在整个频带内增益均大于11 dB且幅值基本保持不变;天线通过频扫方式其E面主波束探测角可以达到78°;该天线高增益、小尺寸,天线的频扫特性使引信在不同落角情况下均能保持对目标的最大探测能力.     

毫米波基片集成波导裂缝阵列天线研究

毫米波基片集成波导裂缝阵列天线具有频带宽、辐射效率高和剖面薄等优点,对实现毫米波雷达导引头的小型化研制工作具有重要的工程意义。根据基片集成波导理论,采用阵列天线设计方法,研究了基于微带贴片加载形式的单元裂缝天线频率带宽拓展方法;基于基片集成波导的平面馈电网络设计方法,设计了16×12微带贴片加载的基片集成波导裂缝阵面结构、并馈基片集成波导功率分配及和差波束形成网络,使用HFSS对天线模型进行了仿真分析和优化设计,研制了毫米波频段单脉冲基片集成波导裂缝阵列天线样机实物。经测试,天线带宽大于1 GHz,效率优于30%,驻波小于2,厚度仅为4 mm,指标测试结果与设计相符合。     

适用于卫星导航系统的双频段圆极化微带天线

随着卫星导航技术的发展,可同时工作于双频段或多频段的接收天线近年来得到日益广泛的关注。本文设计了两种可工作于北斗-B3(1.268 GHz)和GPS-L1(1.590 GHz)双频段的低剖面圆极化微带天线。一种由一个天线单元实现双频带工作;另一种由五个单元的小型天线阵列实现,阵列中心单元工作在较高频段,周围四个相同的单元工作在较低频段。为了满足卫星导航天线低剖面、小尺寸的应用需求,两种天线均选用了较高介电常数的介质基板并采用层叠结构。同时,使用威尔金森功分器,通过双馈法实现圆极化,有效展宽了天线的圆极化带宽,使天线具有良好的圆极化性能。     

新型超宽带双极化天线设计

本文设计了一种在3. 2～18 GHz频率范围工作的超宽带双极化天线。天线单元为双开槽Vivaldi天线,基于共形波纹边缘的设计思想,利用指数形槽缝波纹边缘使双开槽Vivaldi天线在与同尺寸传统Vivaldi天线相近的带宽内获得了高增益等良好的辐射特性。通过将两个双开槽Vivaldi天线正交放置,实现了超宽带双极化天线的设计,测试结果表明,工作频带内的极化隔离度高于25 dB,增益高于7 dB,辐射特性良好。与利用两传统Vivaldi天线实现双极化相比,避免了天线辐射结构的交叉,降低了设计的复杂度。     

与弹头共型的超宽带微带引信天线

针对常规微带天线带宽较窄,难以应用到宽频带系统上的问题,提出了超宽带与弹头共型微带天线。该天线以微带贴片天线为设计基础,在对辐射面宽度渐变处理,开窗以及接地面悬空等特殊结构设计,改善阻抗匹配特性。采用基于有限元方法的电磁仿真软件HFSS对所设计的天线进行仿真与测试结果表明,该天线极大的增加了带宽,在3.6～8.5 GHz的频率范围驻波比小于2.0,其相对带宽达到了68%,且天线在整个工作频段内具有良好的辐射特性。     

Stability of the Third Generation Intensifier under Illumination

The stability under illumination of transmission-mode GaAs photocathode sealed in the third generation intensifier is investigated by use of spectral response testing instruments. The variations of spectral response with the illumination times under weak and intense illumination are compared. The variations of photoemission performance parameters are also characterized. The results show that during initial several weak illuminations photocathode behaves no evident decay and a maximum sensitivity is achieved, while under intense illumination the sensitivity of photocathode begin to decrease largely at the first illumination. The calculated performance parameters show that the variation of surface escape probability with illumination times is a direct cause of instability of photocathode. It is also found that under intense illumination peak wavelength is moved towards short-wave and peak response is decreased, which shows that the ability of long-wave response of photocathode is decreased.     

Passive Acoustic Radar for Detecting Supersonic Cruise Missile

A Passive Acoustic Radar is presented as a necessary complement to electromagnetic wave radar, which will be expected to be an effective means for detecting cruise missiles. Acoustic characteristics of supersonic flying projectiles with diverse shapes are expounded via experiment. It is pointed out that simulation experiment could be implemented using bullet or shell instead of cruise missile. Based on theoretical analysis and experiment, the ““acoustic fingerprint““ character of cruise missile is illustrated to identify it in a strong noise environment. After establishing a locating mathematical model, the technique of acoustic embattling is utilized to resolve a problem of confirming the time of early-warning, considering the fact that velocity of sound is much slower than that of light. Thereby, a whole system of passive acoustic radar for detecting supersonic cruise missile is formed.     

Design and Analysis of Test Schemes of Static Postponing Time on Shrapnels Used to Riot Control

The test scheme of static postponing time given in our actual national military test standard on shrapnels used to control riot is a nine-point test scheme on the combined action of three kinds of temperatures and three kinds of pressures,the consumed ammunitions are more excessive. Statistic analysis and tentative checkout about a lot of test data are done,feasibility gists are put forward for optimizing of the test design scheme. The optimizing design and data analysis of test scheme of the item are done by managing uniformity design theory, two scientific and reasonable six-point test schemes are confirmed. The feasibility and reliability of the optimizing design schemes put forward above are proved ulteriorly by test validating. The gained schemes not only have good design uniformity and little ammunition wastage and meet the test demand, but also have better forecast ability for the result data of other points using the mathematic models from the actual test points.     

Super-resolution Restoration of Remote-sensing Images

A novel image restoration scheme, which is super-resolution image restoration algorithm Poisson-maximum-afterword-probability based on Markvo constraint （MPMAP） combined with evaluating image detail parameter D, has been proposed. The advantage of super-resolution algorithm MPMAP incorporated with parameter D lies in the fact that superresolution algorithm MPMAP model is discrete, which is in accordance with remote-sensing imaging model, and the algorithm MPMAP is proved applicable to linear and non-linear imaging models with a unique solution when noise is not severe. According to simulation experiments for practical images, super-resolution algorithm MPMAP can retain image details better than most of traditional restoration methods; at the same time, the proposed parameter D can help to identify real point spread function （PSF） value of degradation process. Processing result of practical remote-sensing images by MPMAP combined with parameter D are given, it illustrates that MPMAP restoration scheme combined PSF estimation has a better restoration result than that of Photoshop processing, based on the same original images. It is proved that the proposed scheme is helpful to offset the lack of resolution of the original remote-sensing images and has its extensive application foreground.     

Design and Simulation of TF and TA Controller for Missile

A nonlinear terrain following(TF) and terrain avoidance(TA) controller is proposed for missile control systems. Based on classical TF algorithm (adaptive angle method), a new method for TF controller is proposed by using angle of attack. A method of obtaining terrain outline data from digital elevation map (DEM) for TF control is discussed in order to save store space. A TA algorithm is proposed by using bank-to-turn technique. The block control model, which is suitable for backstepping design, is given for nonlinear model of missile. Making full use of the characteristics of the system and combining block control principle and backstepping technique, a robust controller design method is proposed. Uncertainties in every sub-block are allowed, and can be canceled by using the idea of nonlinear damping. It is proved that the state tracking errors are converged to a neighborhood of the origin exponentially. Finally, nonlinear six-degree-of-freedom simulation results for the missile model are presented to demonstrate the effectiveness of the proposed control law.     

Design of Non-fragile Satisfactory Estimator for Linear Continuous Perturbed Stochastic Systems

The design problem of non-fragile estimator is addressed for a class of perturbed linear continuous systems. The perturbations occur on the plant and estimator parameters. The estimator designed should force the error system to achieve the desired decay rate and force the steady error variance less than the specified upper bound irrdevancy of the admissible plant perturbations and estimator perturbations. Consistency problem of the decay rate with the variance upper bound is first considered via linear matrix inequality （LMI） approach. The solution of the estimator parameter under specifications to be consistent is then discussed. The consistency condition of specifications and estimator parameter solution are transformed to feasible or minimum problems subject to a set of LMI respectively. The method is illustrated by a numerical example.     

An Improved Scene-based Nonuniformity Correction Algorithm for Infrared Focal Plane Arrays Using Neural Networks

The improved scene-based adaptive nonuniformity correction （NUC） algorithms using a neural network （NNT） approach for infrared image sequences are presented and analyzed. The retlna-like neural networks using steepest descent model was the first proposed infrared focal plane arrays （IRFPA） nonuniformity compensation method, which can perform parameter estimation of the sensors over time on a frame by frame basis. To increase the strength and the robustness of the NNT algorithm and to avoid the presence of ghosting artifacts, some optimization techniques, including momentum term, regularization factor and adaptive learning rate, were executed in the parameter learning process. In this paper, the local median filtering result of Xij （ n ） is proposed as an alternative value of desired network output of neuron Xij （ n ）, denoted as Tij （ n ）, which is the local spatial average of Xij （ n ） in traditional NNT methods. Noticeably, the NUC algorithm is inter-frame adaptive in nature and does not rely on any statistical assumptions on the scene data in the image sequence. Applications of this algorithm to the simulated video sequences and real infrared data taken with PV320 show that the correction results of image sequence are better than that of using original NNT approach, especially for the short-time image sequences （several hundred frames） subjected to the dense impulse noises with a number of dead or saturated pixels.     

Piecewise Filter of Infrared Image Based on Moment Theory

The disadvantages of IR images mostly include high noise, blurry edge and so on. The characteristics make the existent smoothing methods ineffective in preserving edge, To solve this problem, a piecewise moment filter （PMF） is put forward. By using moment and piecewise linear theory, the filter can preserve edge. Based on the statistical model of random noise, a related-coefficient method is presented to estimate the variance of noise. The edge region and model are then detected by the estimated variance. The expectation of first-order derivatives is used in getting the reliable offset of edge. At last, a fast moment filter of double-stair edge model is used to gain the piecewise smoothing results and reduce the calculation. The experimental result shows that the new method has a better capability than other methods in suppressing noise and preserving edge.     

Bistatic Sonar Localization Based on Best Linear Unbiased Estimation

A best linear unbiased estimation （BLUE） algorithm for bistatic sonar localization is proposed. The Cramer-Rao bound for bistatic Sonar and the geometrical dilution of precision （GDOP） in different conditions are given. The simulation results show that the location accuracy of BLUE algorithm is higher than the weighted least square method.     

Research on Gear-broken Fault Diagnosis in a Tank Gearbox

A fault diagnosis method of working position gear in a tank gearbox is put forward based on simulating the fault of working position gear in an actual tank, extracting the envelope of vibration signal by Hilbert transformation amplitude demodulation method, and zooming the low-frequency band to envelope signal.