一种小型具有双阻带特性的超宽带天线设计

提出了一种具有双阻带特性的共面波导馈电超宽带天线。通过在辐射单元上开E型槽实现了3.75 GHz的第一个陷波结构,并在地板上开两条对称槽实现5.5 GHz的第二个陷波结构。文中提出的具有阻带特性超宽带天线的实测结果与仿真结果吻合较好。除了两个期望的阻带外其他超宽带频段内,该天线满足VSWR<2。同时给出了仿真辐射方向图和增益图。     

一种CPW-fed的双陷波超宽带天线的设计

设计了一种小型双阻带超宽带天线.天线采用共面波导(CPW)馈电的地板结构,地板由两个半椭圆构成,从而实现了超宽带天线及小型化.通过开双U型缝隙实现了双阻带特性,阻带带宽分剐是650 MHz和590 GHz.天线实物测量结果表明,天线驻波比<2的带宽为2.97～12.75 GHz,在整个频段内天线增益较高,同时方向图全向...     

小型化陷波超宽带天线

针对超宽带通信系统（3．1～10．6GHz）与WLAN工作频段（5．15～5．825GHz）之间存在的电磁干扰,本文提出了一种小型化陷波超宽带天线。该天线结构简单,体积较小,陷波特性良好。通过在介质板上侧的金属地板刻蚀C形槽缝可以使天线在5．15～5．825GHz频段实现良好的陷波特性,而且调节C形槽缝的长度可以调节阻带的频段。研究结果表明,该天线的辐射特性良好,能够广泛应用于超宽带通信系统。     

一种紧凑型超宽带双陷波天线设计与研究

超宽带(UWB)系统的工作频段与现有的许多窄带系统频段相互重叠,因此各个系统信号之间存在潜在的干扰。针对上述问题提出了一种紧凑型超宽带双陷波天线。天线由一个圆形辐射贴片构成并通过50W的微带线进行馈电。接地板和传统的接地板相比被截短了,以提高天线的阻抗带宽。通过在辐射贴片上刻蚀H 型槽来实现天线的双陷波功能,并在微带馈线中引入了嵌入式谐振回路(ERC)结构,加大了天线的陷波深度和阻带宽度,陷波性能好于同频段的双陷波天线。仿真和测试结果表明,天线在3.1～4.2 GHz 以及5.0～6.6GHz 具有陷波特性,有效地避免了WiMAX 和WLAN 频段信号的干扰。同时在2.8 ~10.7 GHz 的其它频段上具有良好的阻抗匹配和较好辐射方向特性。天线的尺寸为34mm*26mm*1.6 mm,结构较为紧凑。     

一种双阻带椭圆单极子UWB天线的设计

通过仿真与实际测试结合的方法,研究并设计了一种用于UWB通信的、具有双阻带特性的紧凑椭圆单极子天线。双阻带特性是通过在辐射单元上插入一个缝隙和在馈线上引入一共面波导谐振单元实现的。测试结果表明此天线在3.45~3.75 GHz(覆盖了WIMAX频段)和5~6 GHz(覆盖了5.15~5.85 GHz的WLAN频段)分别有两个阻带,此外,驻波系数在3.1~10.6 GHz UWB的范围内小于2。天线的辐射特性也近似于全向。天线的增益和传输函数也证实了天线能达到双阻带特性。     

一种小型双陷波超宽带天线的设计

设计了一种小型双阻带的超宽带天线。采用由两个半椭圆和一个长条矩形复合的一种新型地板结构,从而实现了超宽带天线小型化。通过开双U型缝隙实现了双阻带特性,阻带带宽分别是540 MHz和610 MHz。天线实物测量结果表明,天线驻波比＜2的带宽为2.7~12 GHz,在整个频段内天线增益较高,同时方向图全向特性良好。天线的测量结果和仿真结果有较好的一致性。     

具有陷波特性的超宽带印刷天线设计

设计一种具有陷波特性的超宽带印刷天线,天线采用圆形金属贴片作为辐射单元,采用微带线进行馈电,通过在贴片上开四个对称T形槽来实现陷波功能。利用仿真软件HFSS10．0对其进行计算,对天线的阻抗特性、方向图和增益进行了研究。运算结果表明,该天线在2．26～4．94GHz和6～11．68GHz的工作频带范围内电压驻波比（VSWR）小于2;在4．94～6GHz的阻带范围内具有良好的陷波特性;在阻带中心频率（5．48GHz）处,电压驻波比高达40。     

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。     

一种高隔离度的双阻带超宽带MIMO天线设计

针对无线通信系统中的超宽带传输要求,设计了一种以FR4为基板的高隔离度的双阻带超宽带MIMO天线。天线由两个辐射单元组成,两个天线辐射单元结构相同,采用了微带馈电的馈电方式。该MIMO天线单元为U型的超宽带单极子天线,通过在天线单元上刻制两个U型槽,使得在天线的工作频率上添加了用于WiMAX和WLAN的阻带。在两个单元天线中间,引入了一条T型地板枝节作为隔离结构,用于改善MIMO天线的隔离度。经网络矢量分析仪测试结果表明,该天线覆盖在2.44～10.75 GHz,且隔离度全部低于-22 dB,拥有较高的隔离度,最大增益为6.76 dB,在实际工程应用当中可以满足UWB无线通信的要求。     

毫米波宽带双陷波MIMO天线设计

为有效抑制部分毫米波通信信号干扰,实现无线通信设备小型化,设计了一款具有双陷波特性的毫米波宽带MIMO天线。天线基本单元由辐射单元、微带馈线、Rogers RO4350B基板以及接地板构成。通过在天线辐射贴片刻蚀U型槽,以及接地板添加倒U型枝节,可在工作频段内产生双陷波特性;进一步在接地板引入圆形开槽使MIMO天线获得良好的隔离度。该天线结构紧凑,尺寸仅为26.7 mm×16.67 mm×1.524 mm,工作于21～40 GHz频段,其中陷波频段为22.04～24.72 GHz和25.96～31.2 GHz。结果表明：该天线在工作频段内隔离度大于20 dB,最大增益可达8.49 dBi,包络相关系数(ECC)均小于0.002,具有良好的辐射和增益性能,在毫米波超宽带通信中具有应用潜力。     

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.     

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.     

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.