K波段高增益超材料微带天线的拓扑优化设计

超材料微带天线的设计通常依赖经验,其中超材料基元的设计多以尺寸优化和形状优化为主。研究了常规超材料对微带天线增益性能的影响,发现其对增益性能的提升效果有限。提出了一种基于遗传算法的高增益超材料微带天线拓扑优化设计方法,对超材料基元采用整体设计的方法,以天线增益最大化为设计目标,以覆铜贴片方格子的有无为设计变量,建立了K波段(24 GHz)超材料微带天线的拓扑优化模型。进而基于遗传算法的求解策略,获得了一种新颖的超材料微带天线构型。仿真结果表明优化后的超材料微带天线侧向辐射得以抑制,其最大增益提升到10.5 dB,与普通微带天线相比性能提升了35%。同时通过改变覆铜贴片格子的布置规模对优化设计结果的收敛性进行分析,分析结果显示创新构型超材料微带天线设计结果是收敛的,且10*10方格子规模下的创新构型制备性价比最高。最后研究了超材料基元单独设计与整体设计的天线工作频率匹配对比,对比结果证实了超材料基元采用整体设计对于超材料微带天线拓扑优化是非常必要的。     

介质加盖高增益微带天线的优化

本文提出了利用点源增益优化方法设计介质加盖的高增益微带天线的方法,所确定的各介质层的电厚度能保证天线取得最高的增益。同时优化计算量也成倍减少。所设计的一个两层介质加盖微带天线的最高增益达到16.8dB。分析结果还表明,在一定条件下,增益和效率是可以兼顾的,用加盖的方法提高天线增益的同时仍可使天线具有较高的辐射效率。     

C波段超材料基板高增益微带天线

针对普通微带天线增益较低的缺点,在普通微带天线上引入带有双面树枝状结构的新型负磁导率材料作为天线的基板,设计了中心工作频率为5.28 GHz的微带天线,对此天线的性能进行了研究.结果表明,通过引入负磁导率材料,天线的性能有了显著的改善,侧向辐射减弱,前向辐射增强,相对于普通微带天线,负磁导率材料微带天线的增益最大提高了2.47 dB,E面方向图的半功率波束宽度收缩了21.93°.     

单馈点宽带圆极化微带天线设计

设计了一种单点馈电的宽带圆极化微带天线。针对微带天线带宽窄的问题,采用双层矩形贴片的层叠结构,通过辐射贴片之间的谐振耦合使天线的频带展宽,得到了良好的效果。在保证天线增益性能的基础上,增加了天线圆极化带宽。采用商用仿真软件HFSS对天线结构尺寸进行了优化设计,仿真结果显示,该天线工作于L波段时,VSWR<2的阻抗带宽达到10%,轴比特性良好,且在整个带宽范围内,天线增益和辐射方向图保持良好的一致性。     

基于FSS的宽带高增益微带天线

针对传统法布里-珀罗(Fabry-Perot,FP)谐振天线增益带宽窄的问题,提出了一种在宽带范围内满足谐振条件的新型频率选择表面(Frequency Selective Surface,FSS)覆层结构。基于覆层反射相位斜率为正原理,设计了具有良好特性的双层FSS结构,并集成到单层介质板,将其作为微带天线的覆层,制备了一种新型宽带高增益微带天线。仿真和实测结果均表明,与微带天线相比,加载FSS覆层结构后的天线增益能在更宽频带内得到提高,并能明显降低天线剖面。     

基于拓扑优化的微带天线奇异方向图设计

拓扑优化方法避免了结构的参数化扫描,直接优化材料排布,用于无源微波器件设计,可极大程度拓展设计解域。文中基于拓扑优化方法研究了微带天线的奇异辐射方向图设计。首先分析了具有奇异辐射方向图的伴随敏感度,其次构建了基于过渡边界条件的二维金属优化模型,再次提出了针对奇异辐射的多种目标场函数,分别实现了高增益定向指向波束、等幅双波束和任意方向线极化波束等奇异方向图。为验证算法有效性和准确性,最后加工并测试了具有高增益指向偏转方向图的微带天线,测试结果与拓扑优化结果吻合较好。此方法特别适合具有复杂目标的无源电磁器件设计。     

介质加盖高增益微带天线的优化

本文提出了利用点源增益优化的设计介质加盖的高增益微带天线的方法，所确定的各介质层的电厚度能保证天线取得同的增益。同时优化计算量也成倍减少，所设计的一个两层介质加盖微带天线的最高增益达到１６．８ｄＢ。分析结果还表明，在一定条件下，增益和效率是可以兼顾的，用加盖的方法提高天线增益同时仍可使具有较高的辐射效率。     

基于零折射超材料的双频高增益微带天线*

基于双面对称单环开口谐振器对结构奇异的电磁特性,设计了一种频率可控的各向异性零折射超材料。将这种零折射超材料应用于普通双频微带天线,制备了中心频率为5. 15GHz 和6. 8GHz 的零折射双频微带天线。仿真和测试结果显示,由于零折射超材料的引入,天线的侧向辐射减弱,方向性增强。在低频工作时,零折射微带天线E 面和H 面半功率波束宽度分别减小了29°和10°,增益提高了2. 2 dB。在高频工作时,零折射微带天线E面和H 面半功率波束宽度均减小了16毅,增益提高了2. 4 dB。将零折射超材料应用于微带天线的介质基板,为高性能双频微带天线设计提供了有效途径。     

加载人工电磁结构的高增益耐高温天线设计北大核心CSCD

本文设计了一款加载人工电磁结构的耐高温天线，为实现弹载天线共形后增益的提高，采用微带天线加载近零折射率材料层方式实现增益提高。通过在天线外部覆盖天线罩形式实现隔热功能，可实现在罩的上表面持续350℃加热时，实现120s内馈电端口处温度小于100℃。首先设计了一款工作在35GHz处的微带天线，实现最大增益为8dBi，其次通过加载两层近零折射率材料和加天线罩所需地板对电磁波的反射，实现天线增益提高到15.4dBi，远高于单个微带天线增益。后期进行了加工与实测，常温实测结果天线最大增益达到14.5dBi左右，E面和H面波束宽度约在24°左右，实测结果与仿真结果差别不大，不仅实现了对单个微带天线增益的较大提升；而且高温隔热性能满足要求。     

基于各向异性混合介质近零折射率超材料的高增益微带天线

根据斯涅尔定律,透过近零折射率超材料(Near Zero Index Metamaterials,NZIM)的电磁波会变为垂直于超材料表面的高指向性波束。这种特性使NZIM材料被广泛应用于高增益及高定向性天线设计中。基于此,设计一款基于各向异性混合介质近零折射率超材料的高增益微带天线。混合介质超材料单元由F₄BM介质及高纯度铜导体组成。根据金属等离子体理论,金属阵列等离子体频率与入射波谐振频率相近时,会呈现近零介电常数。通过合理调节金属半径及介质单元周期,最终使该混合介质在9.5～10.2 GHz频段内折射率近零且等效阻抗接近1,能够与空气匹配。对基于混合介质超材料的微带天线进行加工测试,结果表明,加载混合介质覆层后,微带天线增益明显提高,最大增益提高4.1 dB。     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

Teleportation of an arbitrary unknown N-qubit entangled state under the controlling of M controllers

A new quantum protocol to teleport an arbitrary unknown N-qubit entangled state from a sender to a fixed receiver under M controllers(M < N) is proposed. The quantum resources required are M non-maximally entangled Greenberger-Home-Zeilinger (GHZ) state and N-M non-maximally entangled Einstein-Podolsky-Rosen (EPR) pairs. The sender performs N generalized Bell-state measurements on the 2N particles. Controllers take M single-particle measurement along x-axis, and the receiver needs to introduce one auxiliary two-level particle to extract quantum information probabilistically with the fidelity unit if controllers cooperate with it.     

Diode-end-pumped Nd:YVO4/LBO lasers with 4.2W continuous-wave output at 457 nm

A continuous-wave (CW) 457 nm blue laser operating at the power of 4.2 W is demonstrated by using a fiber coupled laser diode module pumped Nd: YVO4 and using LBO as the intra-cavity SHG crystal With the optimization of laser cavity and crystal parameters, the laser operates at a very high efficiency. When the pumping power is about 31 W, the output at 457nm reaches 4.2 W, and the optical to optical conversion efficiency is about 13.5% accordingly. The stability of the out putpower is better than 1.2% for 8 h continuously working.     

A rigorous proof of MIMO channel capacity’s increase with antenna number

It is well known that adding more antennas at the transmitter or at the receiver may offer larger channel capacity in the multiple-input multiple-output（MIMO） communication systems. In this letter, a simple proof is presented for the fact that the channel capacity increases with an increase in the number of receiving antennas. The proof is based on the famous capacity formula of Foschini and Gans with matrix theory.     

Call for Papers

正Wireless Body-area Networks The last decade has witnessed the convergence of three giant worlds:electronics,computer science and telecommunications.The next decade should follow this convergence in most of our activities with the generalization of sensor networks.In particular with the progress in medicine,people live longer and the aging of population will push the development of wireless personal networks