宽阻带小型化双频带通滤波器

文中提出了一种具有宽阻带的紧凑型双频带通滤波器,它采用了折叠短路枝节负载谐振器、紧凑型微 带单元谐振器(CMRC)和阶跃阻抗谐振器结构。由于多个谐振器产生了五个可控传输零点(TZ),该滤波器实现了两个 通带之间的良好隔离度以及宽阻带特性。制作并测试了尺寸紧凑的双频带通滤波器实验样品,测试结果显示,第一通 带和第二通带的中心频率/ 插入损耗分别为0. 66 GHz/0. 8 dB 和1. 73 GHz/0. 7 dB,阻带频率高达10. 5 GHz,抑制水平 超过15 dB。     

六边环双模微带带通滤波器

提出了一种新颖、简单的六边环内增加微扰小环的双模带通滤波器结构。微扰小环具有两个可调参数,增加了调整双模的自由度,采用垂直结构的馈电方式,并对其进行优化。优化后的滤波器在通带两侧都产生衰减极点,提高了阻带的抑制能力。该滤波器仿真结果表明通带中心频率为5 GHz,3 dB带宽为27.87%,实测和仿真结果相一致,滤波器尺寸为26 mm×26 mm,保证了滤波器的小型化。     

基于微带-槽线过渡的超宽带滤波器

基于电磁耦合微带-槽线过渡结构,设计了一个结构紧凑、具有陷波和超宽阻带的超宽带带通滤波器。通过嵌入1个终端短路的阶跃阻抗微带枝节和底层的槽线耦合产生1个可调节的陷波;同时,在上层微带输出端添加开路枝节和扇形结构获得超宽阻带的特性。该超宽带带通滤波器的中心频率为6.85 GHz,3dB通带为1.95~13.15GHz,相对带宽达到148%。与以往的超宽带带通滤波器相比,其具有结构简单、尺寸小和带外抑制良好等特点,仿真和测试结构吻合较好。     

基于开路T型结构的小型化超宽阻带滤波器设计

传统滤波器由于寄生通带的存在,其高频阻带性能较差。随着超宽带雷达系统和超宽带通信系统的发展,小型化宽阻带的滤波器已成为一项紧迫的技术课题。该文论述了一种普适性的基于开路T型结构的小型化超宽阻带滤波器结构,这种滤波器和传统滤波器相比,结构极为紧凑,5倍基频范围内的寄生通带均被抑制,而通带性能保持良好。基于此结构实际制作了一个截止频率为2.9 GHz的低通滤波器,测量得到的通带内平均插入损耗仅0.67 dB,带内平均驻波比为1.33,过渡带陡峭,40 dB矩形系数仅1.096,而所测得的阻带从3.23 GHz到10.30 GHz之内谐波抑制大于36 dB,从10.30 GHz到15 GHz之内谐波抑制大于27 dB;该滤波器的长度仅为传统的同类型滤波器的长度的37.1%,面积大大减小。仿真和测量结果表明该类型滤波器同时满足了小型化和宽阻带的性能需求。     

一种新型超宽带带通滤波器的设计与实现

传统的超宽带带通滤波器阻带较窄,不能有效抑制谐波.为了抑制超宽带系统中的高次谐波,进一步提高接收机的灵敏度,在分析叉指谐振器、半圆型缺陷地结构和阶梯阻抗并联枝节结构的基础上,设计了一种新颖的超宽带带通滤波器,该滤波器具有较好的阻带特性.最后使用Agilent N5230A矢量网络分析仪对其进行测试,测试结果表明该滤波器工作频带为3.1～10.6GHz,通带内插损小于1.5dB,上阻带的工作频率可以超过18GHz,抑制电平达到-10dB,能有效抑制谐波.     

小型化宽阻带微带带通滤波器的设计

提出一种小型化宽阻带微带带通滤波器,采用半波长阶跃阻抗谐振器结构,且在不相邻的谐振器之间引入交叉耦合,从而在滤波器的阻带上产生了2个传输零点,使阻带抑制在3.95~13.27 GHz小于-20 dB,使寄生通带在中心频率的3.92倍处。滤波器的最终尺寸仅为12.2 mm×11.5 mm,即0.21λg×0.2λg,相比于传统的发夹型滤波器,此滤波器的体积减小了63.5%,而且实测的结果与仿真结果达到了较好的一致性。所提出的滤波器具有更宽的带外抑制,更小的尺寸,且设计简单,在工程领域具有实际的应用价值。     

一种具有边带陡峭特性的超窄带滤波器

应用LTCC技术,设计了一款带通滤波器。采用开口环谐振结构作为基本谐振单元,利用谐振级之间的耦合产生传输零点,实现边带抑制。给出了开口环谐振结构的等效电路分析,滤波器的通带中心频率为23.2 GHz,3-dB带宽为600 MHz,具有很窄的相对带宽,3-dB相对带宽仅为2.6%。对滤波器进行仿真和优化,结果表明,通带22.9~23.5 GHz内插损小于3 dB,低阻带10~21.1 GHz的衰减大于45 dB,高阻带25.3~40 GHz的衰减均大于30 dB。该滤波器的尺寸为4 mm×3.5 mm×0.45 mm,具有非常好的窄带特性和边带抑制特性。     

一种基于并联T型枝节的宽阻带低通滤波器

针对高低阻抗线结构的平面低通滤波器的阻带不够宽、截止频率的2倍频或3倍频处出现寄生通带、尺寸较大的问题,采用并联T型枝节代替高阻抗传输线的方法,利用T型枝节构成的带阻滤波支路,可以抑制寄生通带,增加阻带宽度,提高滤波器性能。以截止频率为4.25 GHz的七阶切比雪夫低通滤波器为例,实验结果表明,通带插损和回波损耗较小,过渡带陡峭,频率在13 GHz处的衰减低于-20 dB,阻带较宽,可以抑制3次谐波,同时滤波器的体积减小了,改善了滤波器的性能,可为低通滤波器宽阻带和小型化的设计及实现提供参考。     

两种新型结构的共面带线带通滤波器的设计

使用各种开路和短路枝节共面带线(Coplanar Stripline,CPS)谐振器,设计了两种新型结构的带通滤波器,对每一种带通滤波器的结构、集中参数模型与性能参数进行了分析和比较,试验结果表明这两种滤波器具有良好的通带插入损耗和很宽的阻带抑制特性,证明了设计的正确性和可行性。     

SIR带状线带阻滤波器的设计

将具有阻带特性的微带马刺线结构引入到带状线中,设计了一款中心频率为2.32 GHz,相对带宽为9.5%,阻带衰减为50 dB的三阶马刺线式带阻滤波器。相比于传统的并联开路短截线型带阻滤波器,马刺线式带阻滤波器的横向尺寸大为减小,结构更加紧凑。采用SIR(stepped-impedance resonator)结构,按相同指标设计了一款三阶SIR马刺线式带阻滤波器。与马刺线式带阻滤波器相比,SIR马刺线式带阻滤波器结构更为紧凑,纵向尺寸缩小约17%,并具有更好的谐波抑制特性。     

Development of the readout system for waveguide multilayer optical card

Waveguide multilayer optical card （WMOC） is a novel storage device of three-dimensional optical information. An advanced readout system fitting for the WMOC is introduced in this paper. The hardware mainly consists of the light source for reading, WMOC, motorized stages addressing unit, microscope imaging unit, CCD detecting unit and PC controlling ＆ processing unit. The movement of the precision motorized stage is controlled by the computer through Visual Basic （VB） language in software. A control panel is also designed to get the layer address and the page address through which the position of the motorized stages can be changed. The WMOC readout system is easy to manage and the readout result is directly displayed on computer monitor.     

Nanoimprint Lithography -A Next Generation High Volume Lithography Technique

IntroductionNanoimprint Lithography is a well-acknowl-edged low cost, high resolution, large area pattern-ing process. It includes the most promising methods,high-pressure hot embossing lithography (HEL) [2],UV-cured imprinting (UV-NIL) [3] and micro contactprinting (m-CP, MCP) [4]. Curing of the imprintedstructures is either done by subsequent UV-lightexposure in the case of UV-NIL or by cooling downbelow the glass transition temperature of the ther-moplastic material in case of HEL…     

Collinear phase-matching study of terahertz-wave generation via difference frequency mixed in GaAs and Inp

The collinearly phase-matching condition of terahertz-wave generation via difference frequency mixed in GaAs and InP is theoretically studied. In collinear phase-matching, the optimum phase-matching wave hands of these two crystals are calculated. The optimum phase-matching wave bands in GaAs and lnP are 0.95-1.38μm and 0.7-0.96μm respectively. The influence of the wavelength choice of the pump wave on the coherent length in THz-wave tuning is also discussed. The influence of the temperature alteration on the phase-matching and the temperature tuning properties in GaAs crystal are calculated and analyzed. It can serve for the following experiments as a theoretical evidence and a reference as well.     

Effects of the alloy compositions on the phonon-polaritons in ternary mixed crystals

Composition dependence of bulk and surface phonon-polaritons in ternary mixed crystals are studied in the framework of the modified random-element-isodisplacement model and the Bom-Huang approximation. The numerical results for Several Ⅱ - Ⅵ and Ⅲ- Ⅴ compound systems are performed, and the polariton frequencies as functions of the compositions for ternary mixed crystals AlxGa1-xAs, GaPxAS1-x, ZnSxSe1-x, GaAsxSb1-x, GaxIn1-xP, and ZnxCd1-xS as examples are given and discussed. The results show that the dependence of the energies of two branches of bulk phonon-polaritons which have phonon-like characteristics, and surface phonon-polaritons on the compositions of ternary mixed crystals are nonlinear and different from those of the corresponding binary systems.     

Influence of PVK ： NPB hole transporting layer on the characteristics of organic light-emitting devices

A doping system consisting of NPB and PVK is employed as a composite hole transporting layer （CHTL）. By adjusting the component ratio of the doping system, a series of devices with different concentration proportion of PVK ： NPB are constracted. The result shows that doping concentration of NPB enhances the competence of hole transporting ability, and modifies the recombination region of charge as well as affects the surface morphology of doped film. Optimum device with a maximum brightness of 7852 cd/m^2 and a power efficiency of 1.75 lm/W has been obtained by choosing a concentration proportion of PVK ： NPB at 1：3.     

New insert layer structure OLEDs

An insert layer structure organic electroluminescent device（OLED） based on a new luminescent material （Zn（salen）） is fabricated. The configuration of the device is ITO/CuPc/NPD/Zn（salen）/Liq/LiF/A1/CuPc/NPD/Zn（salen）/Liq/LiF/A1. Effective insert electrode layers comprising LiF（1nm）/Al（5 nm） are used as a single semitransparent mirror, and bilayer cathode LiF（1 nm）/A1（100 nm） is used as a reflecting mirror. The two mirrors form a Fabry-Perot microcavity and two emissive units. The maximum brightness and luminous efficiency reach 674 cd/m^2 and 2.652 cd/A, respectively, which are 2.1 and 3.7 times higher than the conventional device, respectively. The superior brightness and luminous efficiency over conventional single-unit devices are attributed to microcavity effect.     

Analysis of error performance on Turbo coded FDPIM

Due to variable symbol length of digital pulse interval modulation（DPIM）, it is difficult to analyze the error performances of Turbo coded DPIM. To solve this problem, a fixed-length digital pulse interval modulation（FDPIM） method is provided. The FDPIM modulation structure is introduced. The packet error rates of uncoded FDPIM are analyzed and compared with that of DPIM. Bit error rates of Turbo coded FDPIM are simulated based on three kinds of analytical models under weak turbulence channel. The results show that packet error rate of uncoded FDPIM is inferior to that of uncoded DPIM. However, FDPIM is easy to be implemented and easy to be combined, with Turbo code for soft-decision because of its fixed length. Besides, the introduction of Turbo code in this modulation can decrease the average power about 10 dBm, which means that it can improve the error performance of the system effectively.     

A method for calculating the center position of collimated light

It is a key problem to accurately calculate beam spots＇ center of measuring the warp by using a collimated laser. A new method, named double geometrical center method （DGCM）, is put forward for the first time. In this method, a plane wave perpendicularly irradiates an aperture stop, and a charge couple device （CCD） is employed to receive the diffraction-beam spots, then the geometrical centers of the fast and the second diffraction-beam spots are calculated respectively, and their mean value is regarded as the center of datum beam. In face of such adverse instances as laser intension distributing defectively, part of the image being saturated, this method can still work well. What＇s more, this method can detect whether an unacceptable error exits in the courses of image receiving, processing and calculating. The experimental results indicate the precision of this method is high.     

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.     

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.