考虑互耦的阵列天线辐射近场近似计算方法

针对大规模阵列天线辐射近场电磁兼容性问题,基于有源单元方向图原理和子阵信息的综合方法计算了大规模阵列天线辐射近场场强的分布。该方法采用等效技术获取大规模阵列天线的端口特性,进一步结合天线单元的远场数据综合分析得到大规模阵列天线的近场分布;计算结果表明,在满足天线单元辐射远场条件下,该方法能够准确计算出大规模阵列天线的辐射近场分布。相较于全波分析,本方法在保证精度的同时,提高了计算效率,并且具有良好的灵活性。通过全波分析的数值算例验证了该方法的正确性。     

Field emission of vertically-aligned carbon nanotube arrays grown on porous silicon substrate

Vertically aligned arrays of multi-walled carbon nanotubes were grown by pyrolysis of acetylene on iron catalytic particles within a porous silicon template via chemical vapor deposition (CVD) at 700 °C. Using this method ordered nanotubes with diameters from 75 to 100 nm could be produced. The diode configuration field emission of the CNT arrays were performed and the onset electric field is 4 V/μm and the emission current can approach 1 mA/cm² at a electric field of 9.5 V/μm. The enhancement factor of the CNT arrays (4012) is derived from the F–N plot of the experiment data. To demonstrate the uniformity of the field emission, an ITO glass substrate with phosphor coated is used as anode in the field emission experiment. The average fluctuation of the emission current density was less than 5%. The result shows that the field emission of the CNT arrays on the silicon substrate is very uniform. These carbon nanotube arrays are useful for applications in field emission displays and sensors. The fabrication method shows the feasibility of integration between carbon nanotube arrays and silicon microelectronics.     

图案化氧化钨纳米线阵列的低温制备工艺及其场发射特性研究

氧化钨纳米线由于具有长径比较大、导电性好、阈值电场较低、可承受的电流较高等优点,因此在场致电子发射器件中受到人们的广泛关注。但是在氧化钨纳米结构研究发展的过程中,出现了一些技术难题,比如制备温度高(>800℃),制备的氧化钨通常混合多种化学相而导致物性不均匀等,所以束缚了氧化钨纳米线在场发射领域的快速发展。本文采用磁控溅射技术结合化学气相沉积技术在500℃下分别实现了高纯相的WO2和WO3纳米线阵列的定域生长。场发射特性研究结果表明:所制备的WO3纳米线阵列的开启电场低至0.65MV/m,阈值电场约为2.9MV/m,最大电流密度达到18.3A/cm2;WO2纳米线阵列的开启电场低至0.8MV/m,阈值电场为2.46MV/m,最大电流密度达到12.1mA/cm2。这表明在低温下制备的氧化钨纳米线阵列在场致电子发射领域具有非常广阔的应用前景。     

Hierarchical interconnection structures for field programmable gatearrays

Field programmable gate arrays (FPGA's) suffer from lower density and lower performance than conventional gate arrays. Hierarchical interconnection structures for field programmable gate arrays are proposed. They help overcome these problems. Logic blocks in a field programmable gate array are grouped into clusters. Clusters are then recursively grouped together. To obtain the optimal hierarchical structure with high performance and high density, various hierarchical structures with the same routability are discussed. The field programmable gate arrays with new architecture can be efficiently configured with existing computer aided design algorithms. The k-way min-cut algorithm is applicable to the placement step in the implementation. Global routing paths in a field programmable gate array can be obtained easily. The placement and global routing steps can be performed simultaneously. Experiments on benchmark circuits show that density and performance are significantly improved     

场发射显示器件阴极研究进展

介绍了场发射显示器件的基本结构和工作原理,分析了传统微尖型阴极发射阵列存在的问题,在此基础上介绍了平面型阴极的组成和工作方式以及目前MISM结构平面阴极的研究进展.     

2D Nanomaterial Arrays for Electronics and Optoelectronics

Two‐dimensional (2D) materials, benefitting from their unique planar structure and various appealing electronic properties, have attracted much attention for novel electronic and optoelectronic applications. As a basis for practical devices, the study of micro/nano‐2D material arrays based on coupling effects and synergistic effects is critical to the functionalization and integration of 2D materials. Moreover, micro/nano‐2D material arrays are compatible with traditional complementary metal oxide semiconductor (CMOS) electronics, catering well to high‐integration, high‐sensitivity, and low‐cost sensing and imaging systems. This review presents some recent studies on 2D material arrays in sequence from their novel preparations to high‐integration applications as well as explorations on dimension tuning. A first focus is on various typical fabrication methods for 2D material arrays, including photolithography, 2D printing, seeded growth, van der Waals epitaxial growth, and self‐assembly. Then, the applications of 2D material arrays, such as field effect transistors, photodetectors, pressure sensors, as well as flexible electronic devices of photodetectors and strain sensors, are elaborately introduced. Furthermore, the recent burgeoning exploration of mixed‐dimensional heterostructure arrays including 0D/2D, 1D/2D, and 3D/2D is discussed. Ultimately, conclusions and an outlook based on the current developments in this promising field are presented.     

图形化氧化锌阵列的制备及其场发射性能研究

为了减小场发射的屏蔽效应,采用图形化技术对氧化锌(ZnO)纳米枝阵列进行调控,并研究图形化ZnO枝阵列的性能。首先采用光刻法在ITO导电玻璃上制备图形化ZnO种子层,再用电沉积法在图形化种子层上生长ZnO纳米枝阵列。利用扫描电子显微镜(SEM)、X射线衍射(XRD)研究所制备的图形化ZnO阵列形貌、结构等,并测试其场发射性能。研究结果表明,制备的图形化ZnO纳米枝是圆阵列,直径为330μm左右,纳米ZnO主干平均直径为400~500nm,发现主干上有一些精细的类似锥状的纳米量级微细枝结构,并且具有良好的场发射性能,开启场强为2.15V/μm,场增强因子为16 109。该图形化生长ZnO阵列阴极的方法是一种能较好改善材料场发射性能的方法,在场发射应用领域表现出较好的前景。     

Arrays for generating arbitrary mask vectors

A circuit for generating mask vectors is described. It can be connected into an array when long mask vectors are required. Such arrays are very useful in any kind of field manipulation, as field extraction, field insertion, shifting etc.     

The design of point detector arrays, I

This paper considers the design of a detection system to optimally detect known signal fields--scalar functions of a vector argument--corrupted by an additive noise field. The detection system has as its inputsnsamples (in Space) of the signal-plus-noise field; each spatial sample is the output of a point detector. Optimal processing of the point-detector outputs, as well as the locations of the point detectors, is considered. For a fixed array and under assumptions that are often physically reasonable, the optimum detector is separable into a spatial combiner and a temporal processor. The probability of error of the optimum detector is a monotonic function of the array gain. Convenient expressions of the array gain are found for circular arrays; by using these expressions, optimal radii for circular arrays are found.     

Field Emitters Using Inverse Opal Structures

Electronics to be used in space must often perform in high temperature or radiation hard environments that render conventional solid‐state technologies unable to meet mission requirements. As a result, microscale and nanoscale field emission devices are being explored as fundamental components of electronics capable of operating in these harsh environments. Wide scale implementation of these devices is hindered by the difficulty of fabricating large, mechanically stable, uniform arrays of sharp emitting tips. This work presents a scalable method to produce uniform arrays of field emitting tips. Polystyrene spheres are applied as a template for electrochemical deposition. An electrochemical etching process is developed to sharpen tips to a radius of curvature of 5–10 nm, optimizing them for field emission applications. The flexibility of the fabrication process allows for device optimization in terms of tip geometry, density, and constituent material to achieve high field enhancement factors, exceeding 100. Miniaturized field emitting diode and gated triode devices are fabricated. Finally, the electrochemically deposited material is used as a scaffold for the deposition of a refractory, low work function emitting layer, and the hybrid cathode is characterized as a field emitter at temperatures up to 300 ºC.     

金属腔体孔阵电磁耦合的数值分析

本文针对正弦调制高斯脉冲激励下金属腔体的孔阵电磁耦合问题，使用Zeland公司的FIDELITY软件进行FDTD仿真，发现面积相同（即通风，散热量相等）时腔体电场耦合能力随着孔阵中孔的数目增多而下降，同时对不同形状孔阵及不同间距孔阵情况进行比较。     

Optimized symmetric discrete line arrays

A generalization of Dolph's method for the synthesis of discrete antenna arrays is applied to six different symmetric line arrays. Based on these examples, it is concluded that 1) the field patterns of optimized symmetric line arrays with the same number of elements and with the same aperture are virtually indistinguishable and 2) optimized arrays with an odd number of elements are substantially better, in general, than arrays with an even number of elements.     

Periodic TiO2 Nanorod Arrays with Hexagonal Nonclose‐Packed Arrangements: Excellent Field Emitters by Parameter Optimization

Periodic TiO₂ nanorod arrays with hexagonal nonclose‐packed (hncp) arrangements are synthesized by pulsed laser deposition (PLD) using polystyrene colloidal monolayers as templates and with subsequent annealing in air. The hncp‐array formation is governed by in situ volume shrinkage of amorphous TiO₂ nanorods in the crystallizing process during annealing. The array periodicity can easily be tuned by different sphere sizes of the colloidal template, whereas the distance between neighboring nanorods can be controlled by altering the background gas pressure during the PLD process, at a given periodicity for the nanorod array. Parameter‐controlled growth is helpful for investigating and optimizing the parameter‐dependent field‐emission properties. The hncp nanorod array exhibits an enhanced field‐emission (FE) performance compared to both particle films and nanorod arrays with top aggregation. With an increase in periodicity of a hncp nanorod array, the field‐enhancement factor decreases and the turn‐on FE field increases. FE characteristics can be further enhanced by increasing the distance between adjacent nanorods while maintaining the same periodicity. The parameter‐optimized results suggest that the arrays with a smaller periodicity and a larger distance display the best FE performance and could be highly valuable for designing field‐emission devices based on these periodic nanorod arrays.     

传输线矩阵(TLM)方法在分析天线阵辐射特性中的应用

本文运用传输线矩阵(Transmission-line Matrix.TLM)方法分析由理想点源构成的直线天线阵的中间区和远区的场特性,并对天线阵的辐射方向图进行了数值计算:本文计算结果与解析分析结果吻合得很好,表明TLM方法是分析天线阵的近区、中间区和远区场的分布特性以及辐射特性的一种较好的方法.     

FPGA设计转换

本文主要论述FPGA(现场可编程门阵列)至其它ASIC实现方式,如门阵或标准单元的设计转换;介绍了设计网表转换,网表优化途径;同时,还讨论了不同厂家FPGA设计之间的转换。提出了适用于不同工艺的转换以及同种工艺不同库之间转换的设计转换思想。     

Periodicity Perturbed Grounded Frequency Selective Surface Arrays as Millimeter Wave Random Phase Coherence Destroying Diffusers

This paper presents the design, construction and testing of perturbed periodicity slot type grounded Frequency Selective Surface (FSS) array as millimeter wave (mm-wave) random phase diffusers to eliminate speckle in active mm-wave imaging. To create a random phase diffuser for destroying the coherence of mm-wave sources we proposed FSS based diffusers arrays where the periodicities between the elements are different thought the slot of the cells are similar. The impacts of periodicity variations of both TM and TE field directions have been investigated. The periodicity of an FSS is the main design parameter used to optimize the phase shifting properties of the arrays. The critical parameters of the diffuser arrays design, such as phase relation with periodicity and optimum designed consideration are discussed. We designed the FSS arrays with Finite Integral Technique, fabricated by using etching technique and characterized the S-parameters with a free space Millimeter Wave Vector Network Analyzer (MVNA).     

Hermite-Rodriguez UWB Circular Arrays

Pulsed circular arrays are collecting growing interest in radar applications such as automotives and indoor navigations. This contribution presents the analytic derivation of the space-time and energy patterns of pulsed circular arrays in terms of geometrical and electrical parameters as well as of the signal distortion produced by the antennas' response. It is shown that the field emitted by circular arrays with many elements can be represented as a summation of a practically finite set of high-order Hermite-Rodriguez waveforms, while the energy pattern is a generalized Hypergeometric Function. The angular and temporal resolutions are finally related, through handy formulas, to the array size, the input signals and to the antenna types.      

基于 RMA 的三维成像与二维 MIMO 阵设计

距离迁移(RM)算法能够精确校正近场距离徙动,同时通过使用快速傅里叶变换可以达到很高的计算效率,具有应用于近场MIMO雷达三维实时成像的潜力。RM算法应用于近场MIMO成像的主要挑战是设计合适的阵列结构。文中利用球面波分解为无穷多个平面波的方法推导了MIMO雷达近场三维RM 成像算法,在深入分析算法实现流程的基础上得 到了RM算法对MIMO阵列构型的四条约束条件。提出了一种适用RM算法的MIMO阵列设计方法,并利用所提方法设计了MIMO阵列,结合仿真,分析了所设计阵列的成像性能。     

Phase-locked arrays of buried-ridge InP/InGaAsP diode lasers

Phased-locked arrays of buried-ridge InP/InGaAsP diode lasers, emitting at 1.3 μm, were investigated both theoretically and experimentally. These arrays consist of index-guided buried-ridge lasers which are coupled via their evanescent optical fields. The field patterns and the modal gains of the array supermodes were calculated by using a simple waveguide model. The theoretical results show that buried-ridge arrays can be designed such that only the fundamental supermode is excited. In that case, the array lasers are coupled in-phase, which yields single-lobed, diffraction limited far-field patterns. The buried-ridge InP/InGaAsP arrays were grown by liquid phase epitaxy. These arrays exhibited single-lobed beams less than 4° in width up to more than twice the threshold current. Comparison of the measured field patterns and the calculated ones indicated that these arrays oscillated mainly in the fundamental supermode.     

Multiring-antenna arrays

Multiring-antenna arrays are considered, particularly for space telemetry and communication. The configuration with two concentric rings is examined. The distant electric field, the radiation resistance, the directive gain and the mutual-coupling impedances are derived. Numerical results are given for arrays with eight monopoles in each ring.