一种改进的小型超宽带天线

为了有效地对超宽带天线进行小型化,通过对平面椭圆单极子超宽带天线进行切半和切边处理,设计了尺寸为10mm×17mm的小型超宽带天线。为了改善因对天线进行切半而恶化的全向辐射特性,在小型超宽带天线的辐射体中引入了缝隙结构。仿真结果表明:改进的小型超宽带天线在整个超宽带频带内具有良好的阻抗匹配和全向辐射特性。该天线的测量结果与仿真结果基本吻合。     

应用于WLAN和WiMAX的双频带印刷天线设计

提出了一种新型的用于WLAN/WiMAX通信系统的双频带印刷单极天线。通过改进的叉子形的辐射贴片,使天线在2.4 GHz频带内谐振。同时,在介质基板背面的引入寄生辐射贴片,利用与正面的辐射贴片的耦合效应,使天线谐振在5 GHz频带内。最终使得天线可以覆盖2.4/5.2/5.8 GHz WLAN 和5.5 GHz WiMAX频带。对加工后的天线模型测试表明,天线在工作频带内具有较好的全向辐射特性和可观的增益。因此,该天线在无线多频带通信系统中具有广泛的应用前景。     

具有多阻带特性的超宽带天线研究与设计

设计一种具有多阻带特性的平面超宽带天线,采用在辐射贴片开C型槽和H型槽的方法实现天线在Wi MAX频段和WLAN频段的带阻抑制特性。U型槽孔产生高于10.6 GHz的高频阻带,同时馈线终端的阶梯结构实现了多频宽带的匹配。该天线在3.16~3.73 GHz,4.63~6.02 GHz以及高于10.6 GHz的超宽带频带内形成阻带,表明其在工作频带内有良好的抗干扰能力。此外,在天线的通带内有良好的全向特性,结果表明该设计方法的有效性。     

具有Parylene 涂层的WLAN 平面柔性天线*

设计了一种用于无线局域网(WLAN)的平面柔性天线。该天线的设计采用厚度为127μm 的聚酰亚 胺薄膜作为天线的印制板,利用电容加载的单极子天线结构,使其获得了柔性和双频宽带的性能。整个天线被 10μm 厚度的Parylene-C 保护涂层所覆盖,使天线具备了良好的防潮、防水等性能。对天线在平面和各种弯曲状态下 的性能进行了测试,测试结果表明,该天线在工作频带内的回波损耗优于10dB,具有较好的全向辐射特性,实验结果 表明该天线可以应用于柔性通信设备中。     

开槽结构椭圆超宽带平面天线设计与研究

提出一种阻抗带宽比为12.9∶1的开槽结构的椭圆平面超宽带天线。该天线的辐射体采用扇形开槽的椭圆结构,而地板为矩形开槽结构,这两处适当位置合适尺寸的开槽使得天线得到了良好的阻抗匹配特性,进而实现了很好的超宽带特性。与以往所提出的超宽带天线相比,本天线尺寸更小,而带宽更宽,实现了在3.1～40GHz频带内反射损耗小于-10dB,在水平面的辐射方向图呈现良好的全向性。仿真和实验证明该天线具有良好的辐射特性及实用性,可以为现今及未来无线通信提供良好的选择。     

一种宽带全向防热天线设计

本文介绍了一种宽带全向防热天线，天线采用锥形金属腔加载防热天线盖板的结构，实现了方位面内波束的 全向覆盖，在低仰角位置具有较高的全向增益。通过理论设计、仿真计算以及实物测试对提出的天线设计方案进行了 深入研究。实测结果表明：在应用的很宽频带内，天线具有良好的驻波比和低仰角全向增益覆盖性。天线测试结果与 仿真结果吻合较好。研究结果表明：本文提出的全向防热天线方案可行，具有良好的应用前景。     

新型Ku频段全向微带阵列天线

设计了一种新型Ku频段全向天线,该天线由双面辐射微带阵列组成,通过串联形式馈电,实现了全向中等增益辐射特性.文中给出了微带阵列天线的设计方法,对该微带阵列天线的阻抗带宽特性、方向图特性和馈电结构进行了分析.结果表明,该微带阵列天线反射损耗小于-10 dB的绝对带宽为1.15 GHz,在可用频带内全向增益为6.8 dB～7.3 dB,E 面波束宽度在20°～24°,H面方向图不圆度在±0.5 dB以内.该天线能够满足微波通信系统要求.     

卫星导航复合多功能桅杆天线的研究

本文利用双寄生套筒的结构,采用双锥和粗振子结合的辐射体形式设计了一款可与卫导天线级联的全向宽带穿杆天线。采用这种特殊结构该天线解决了常规天线内部穿金属接地杆后驻波恶化的问题。仿真和实测结果表明天线在120-550MHz频带内电压驻波比小于2.5,且高低频端的方向图全向性良好。     

一种新型弹载遥测通信天线的设计

为满足因信道容量的扩充而产生的对通信天线更宽频带的需求,提出了一种新型的弹载通信天线结构。采用微带天线结构,通过缝隙加载和共面波导馈电结构,得到宽带小型化天线辐射单元。该天线具有良好的E面全向特性和宽带特性,并且结构紧凑、馈电简单、带宽较宽、易于制造。     

宽带平面直角双频单极天线

对于超宽带系统,需要具备可工作频率为3.1~10.6GHz的宽带天线。本文介绍了四种宽带平面单极天线,分别为圆形平面单极天线、平面直角单极天线、平面双频单极天线和平面直角双频单极天线。其中平面直角单极天线兼具宽频和全向特性,平面双频单极天线和平面直角双频单极天线在两个谐振点都具有宽带特性,平面直角双频单极天线在整个频带内水平面的辐射方向图几乎都可以达到全向。     

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.     

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.     

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.     

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.     

Curved crystal spectrometer for the measurement of X-ray lines from laser-produced plasmas

In order to diagnose the laser-produced plasmas, a focusing curved crystal spectrometer has been developed for measuring the X-ray lines radiated from a laser-produced plasmas. The design is based on the fact that the ray emitted from a source located at one focus of an ellipse will converge on the other focus by the reflection of the elliptical surface. The focal length and the eccentricity of the ellipse are 1350 mm and 0.9586, respectively. The spectrometer can be used to measure the X- ray lines in the wavelength range of 0.2-0.37 nm, and a LiF crystal （200） （2d = 0.4027 nm） is used as dispersive element covering Bragg angle from 30° to 67.5°. The spectrometer was tested on Shengnang- Ⅱ which can deliver laser energy of 60-80 J/pulse and the laser wavelength is 0.35 μm. Photographs of spectra including the 1 s2p ^1P1-1s^2 ^1S0 resonance line（w）, the 1s2p ^3P2-1s^2 1S0 magnetic quadrupole line（x）, the 1s2p ^3P1-1 s^2 ^1S0 intercombination lines（y）, the 1 s2p ^3S~1-1 s^2 ^1S0 forbidden line（z） in helium-like Ti Ⅹ Ⅺ and the 1 s2s2p ^2P3/2-1 s622s ^2S1/2 line（q） in lithium-like Ti Ⅹ Ⅹhave been recorded with a X-ray CCD camera. The experimental result shows that the wavelength resolution（λ/△ 2） is above 1000 and the elliptical crystal spectrometer is suitable for X-ray spectroscopy.     

Preparation and Characterization of TaN ALD Precursors

High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET ＞ PDMAT ＞ TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.     

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.     

Electronic Structure of Semiconductor Nanocrystals

This paper reviews our recent development of the use of the large-scale pseudopotential method to calculate the electronic structure of semiconductor nanocrystals, such as quantum dots and wires, which often contain tens of thousands of atoms. The calculated size-dependent exciton energies and absorption spectra of quantum dots and wires are in good agreement with experiments. We show that the electronic structure of a nanocrystal can be tuned not only by its size,but also by its shape. Finally,we show that defect properties in quantum dots can be significantly different from those in bulk semiconductors.