Interleaved thinned linear arrays

This paper presents three approaches to improving the efficiency of an array aperture by interleaving two arrays in the same aperture area. The interleaved arrays have aperiodic spacings that are integer multiples of a set minimum spacing and are optimized to reduce the maximum sidelobe level. Fully and partially interleaved sum arrays operating at the same frequencies are demonstrated as well as interleaved sum and difference arrays for a monopulse system. A genetic algorithm is used to optimize arrays of isotropic point sources as well as arrays of dipoles modeled using the method of moments. Narrow beamwidths are possible while avoiding high sidelobes. The available aperture area is efficiently used.     

Planar beam-lead gallium arsenide electroluminescent arrays

The application of planar and beam-lead technologies to GaAs has permitted the fabrication of integrated arrays of electroluminescent diodes. The arrays, to date, have consisted of 4 × 4 matrices, and larger arrays are now considered to be feasible. The diodes are Zn-diffused on 0.010-in centers, with Zn masking being provided by a composite structure of thermally deposited SiO2and phosphosilicate glass layers. Air isolation is used between the individual diodes with the interconnections being made by means of the beam leads. External efficiencies for light exiting from the back of the arrays have been as high as 0.003 with the variation within the arrays being less than ± 10 percent. The arrays have been used to optically trigger matching arrays of Si photosensitive p-n-p-n's. They also show promise in memory applications, where they may compete favorably with laser activated memory systems.     

Phased array theory and technology

This review of array antennas highlights those elements of theory and hardware that are a part of the present rapid technological growth. The growth and change in array antennas include increased emphasis on "special-purpose" array techniques such as conformal and printed circuit arrays, wide angle scanning arrays, techniques for limited sector coverage, and antennas with dramatically increased pattern control features such as low sidelobe, adaptively controlled patterns. These new topics have substantially replaced large radar arrays in the literature and constitute a major change in the technology. The paper presents a tutorial review of theoretical developments emphasizing techniques appropriate to finite arrays, but indicating parallel developments in infinite array theory, which has become the useful tool for analysis of large arrays. A brief review of the theory of ideal arrays is followed by a generalized formulation of array theory including mutual coupling effects, and is appropriate to finite or infinite arrays of arbitrary wire elements or apertures in the presence of a conducting ground screen. Some results of array tolerance theory are summarized from the literature and retained as reference throughout discussions of array component requirements and device tolerance for low sidelobe arrays. Examples from present technology include conformal and hemispherical coverage arrays, lightweight printed circuit arrays, systems for use with reflectors and lenses in limited sector coverage applications, and wide-band array techniques.     

One-, Two-, And Three-Dimensional Arrays

The performances of one-, two-, and three-dimensional arrays are reviewed and related to the spherical modes of free space. The characteristics of interferometers, ring arrays, and highly thinned arrays are also considered as special cases.     

Scan-independent slot arrays with parasitic wire arrays in astratified medium

The effect of a parasitic wire array on the scan admittance of a slot array has been investigated. Structures considered can consist of an infinite slot array and an arbitrary number of parasitic infinite arrays of piecewise linear wires, all arrays being embedded in a stratified medium. These include, as particular cases, phased arrays of Clavin elements. Expressing the fields from the arrays as plane waves, a procedure similar to the periodic moment method for infinite periodic structures is set up to obtain the scan admittance of the slot array. Scan admittances are presented for a slot array with monopole arrays in free space, and a slot array with a tilted dipole array in a stratified medium. Blind spots at which the incident energy is mainly reflected rather than transmitted were found. Results obtained indicate the possibility of using parasitic wire arrays for scan compensation of active slot arrays     

Very large arrays of flip-chip bonded 1.55 μm photodetectors

We present very large arrays of InGaAs-InP p-i-n photodetectors flip-chip bonded to Si. The photodiodes are designed for operation at zero bias, e.g., for spectroscopic applications. Our design maintains depletion at zero bias resulting in ~99% photocurrent collection efficiency. The series resistance of our photodiodes is <1 Ω for a 40×40 μm device, including the flip-chip bond, resulting in high tolerance to shunt leakage. We produce arrays of photodiodes as large as 120 and measure leakage currents. We analyze zero-bias photocurrent generation in the presence of leakage and determine that with this technology arrays as large as 128 can be produced with high yield. The concept of redundancy in zero-bias photodiode arrays is presented and explored. Under the assumption that photodiode leakage is produced by microscopic point defects, a substantial increase in uniformity can be achieved in photodetector arrays by employing redundancy     

A flexible approach to emitter-coupled logic arrays

The ECCSL arrays have been successfully fabricated using two levels of metalization on 120 by 120-mil chips. The yield, fabrication, and performance studies of these arrays, while not yet complete, indicate that current mode logic arrays of 10 to 30 gates are entirely feasible. This is especially true if the size of the chips are reduced as much as possible (preferably below 0.10 by 0.10 inch.) Indications are that arrays with relatively low gate counts (10 to 30 gates) greatly reduce the testing problems usually associated with array technology.     

Nanoarchitectured Design of Vertical-Standing Arrays for Supercapacitors: Progress,Challenges, and Perspectives

Vertical-standing arrays have aroused great enthusiasm as electrode materials for supercapacitors in recent years owing to their structural and compositional characteristics. Although significant efforts have been made in the construction of vertical-standing arrays with tailored compositions and architectures, an in-depth understanding of the relevant structure–activity relationships has not yet been reviewed in detail. Herein, recent important progress in controllably synthesizing vertical-standing arrays as well as their application as supercapacitors is reviewed. Afterward, promising strategies to improve the electrochemical performance of vertical-standing arrays are discussed. Finally, the challenges and possible directions for developing vertical-standing arrays with outstanding performance are outlined. This review provides important guidelines for designing and regulating vertical-standing arrays and constructing desirable electrode materials for future electrochemical energy storage.     

Perfect ternary arrays

Signals of two or more dimensions with ideal impulse-like periodic autocorrelation functions are used in higher-dimensional signal processing or in radar systems. Four synthesizing methods for perfect ternary arrays are presented. Based on known perfect binary and ternary sequences and arrays, many new perfect ternary arrays with increasing number of elements are constructed. New strong conditions for the existence of perfect arrays are developed. By combining these conditions with an advanced computer search, new ternary arrays are found. These new ternary arrays can be used as starting arrays to construct additional perfect ternary sequences and arrays     

量子点阵列光致荧光谱温度依赖性研究

多模量子点阵列的光致荧光(PL)光谱的温度依赖性研究对于实现高效的量子点光电器件有着非常重要的意义.利用速率方程模型模拟不同密度量子点阵列中的载流子动力学过程.研究表明,高密度量子点阵列中不同尺寸量子点族的PL强度表现不同的温度依赖关系;而低密度量子点阵列不同点族PL强度均随温度衰减.高密度量子点阵列中,载流子被热激发到浸润层后,部分地被大量子点再俘获,即在量子点族间转移;低密度量子点阵列中不同量子点族间的载流子转移受到限制.不同量子点族光致荧光强度比的最大值强烈地依赖于量子点的激活能差.     

修正MUSIC算法对非线性阵列适用性的讨论

以三个单极子组成的均匀线性阵和三个单极子\交叉环组成的非线性阵为例,通过使用MMUSIC算法分别对他们接收到的包含两个目标的模拟海杂波数据进行处理后提取的目标到达角参数是否正确,检验MMUSIC算法对非线性天线阵的适用性,得出MMUSIC算法对均匀线性阵适用,对非线性阵列不适用的结论,并分析了原因.     

液晶光阀组式光刻快门控制电路的研究与设计

通过分析光刻快门的控制原理及结合液晶光阀的工作原理．对液晶光阀组的控制进行了研究并给出了其控制电路图，该控制系统采用DS75451与门模块对液晶光阀组进行驱动，通过AT89C51单片机控制液晶光阀组的亮暗．实现了对液晶光阀组的控制．起到光刻快门的作用。通过实际光刻试验．液晶光阀组式光刻快门机构可以完成编码图案的控制，通光控制达到了预计的要求．刻出的图案清晰，线条陡直．证明液晶光阀替代穿孔带用于光刻快门是完全可行的。     

Design of different planar geometries of antenna arrays for isoflux radiation in GEO satellites

The synthesis of different planar geometries of antenna arrays for isoflux radiation is presented in this paper. This synthesis considers the reduction of the side lobe level and the isoflux radiation requirements for Geostationary Earth Orbit satellites. The behavior of the radiation is studied in three geometries of two-dimensional antenna arrays such as uniform planar arrays, aperiodic planar arrays (APA) and concentric ring arrays (CRA). The well-known methods of genetic algorithm and particle swarm optimization are utilized for the optimization problem. In this way, the designs of APA and CRA presented in this paper could provide an acceptable solution for reducing the antenna hardware and simplifying the power feeding even more than results presented previously in the literature.     

A NOVEL UNIVERSAL PREPROCESSING APPROACH FOR HIGH-RESOLUTION DIRECTION-OF-ARRIVAL ESTIMATION

A novel universal preprocessing method is proposed to estimate angles of arrival,which is applicable to one-or two-dimensional high resolution processing based on arbitrarycenter-symmetric arrays (such as uniform linear arrays, equal-spaced rectangular planar arraysand symmetric circular arrays). By mapping the complex signal space into the real one, the newmethod can effectively reduce the computation needed by the signal subspace direction findingtechniques without any performance degradation. In addition, the new preprocessing scheme itselfcan decorrelate the coherent signals received on the array. For regular array geometry such asuniform linear arrays and equal-spaced rectangular planar arrays, the popular spatial smoothingpreprocessing technique can be combined with the novel approach to improve the decorrelatingability. Simulation results confirm the above conclusions.     

Efficient coding schemes for the hard-square model

The hard-square model, also known as the two-dimensional (2-D) (1, ∞)-RLL constraint, consists of all binary arrays in which the 1's are isolated both horizontally and vertically. Based on a certain probability measure defined on those arrays, an efficient variable-to-fixed encoder scheme is presented that maps unconstrained binary words into arrays that satisfy the hard-square model. For sufficiently large arrays, the average rate of the encoder approaches a value which is only 0.1% below the capacity of the constraint. A second, fixed-rate encoder is presented whose rate for large arrays is within 1.2% of the capacity value     

基于Parylene的柔性微电极阵列微加工工艺研究

基底集成的柔性微电极阵列(MEAs)从一个全新的角度演绎了植入式神经系统,对神经进行电刺激并记录神经电信号.以一种新型聚合物材料聚对二甲苯(parylene)为基底,制备出了用于神经接口的柔性神经微电极阵列.采用MEMS加工技术,设计了一种基于parylene柔性神经微电极阵列的加工工艺方法,并讨论了在流片过程中的关键问题,如掩膜层的选择、电极的剥离及焊接与封装等.该柔性微电极阵列在用于视觉假体的神经接口方面具有独特的应用优势.     

Antenna applications of superconductors

The applicability of superconductors to antennas is examined. Potential implementations that are examined are superdirective arrays; electrically small antennas; tuning and matching of these two; high-gain millimeter-wavelength arrays; and kinetic inductance slow wave structures for array phasers and travelling wave array feeds. It is thought that superdirective arrays and small antennas will not benefit directly, but their tuning/matching networks will undergo major improvements. Miniaturization of antennas will not be aided, but much higher gain millimeter-wave arrays will be realizable. Kinetic inductance slow-wave lines appear advantageous for improved array phasers and time delay, as well as for traveling-wave array feeds     

Source localization with distributed sensor arrays and partial spatial coherence

Multiple sensor arrays provide the means for highly accurate localization of the (x,y) position of a source. In some applications, such as microphone arrays receiving aeroacoustic signals from ground vehicles, random fluctuations in the air lead to frequency-selective coherence losses in the signals that arrive at widely separated sensors. We present performance analysis for localization of a wideband source using multiple, distributed sensor arrays. The wavefronts are modeled with perfect spatial coherence over individual arrays and frequency-selective coherence between distinct arrays, and the sensor signals are modeled as wideband, Gaussian random processes. Analysis of the Cramer-Rao bound (CRB) on source localization accuracy reveals that a distributed processing scheme involving bearing estimation at the individual arrays and time-delay estimation (TDE) between sensors on different arrays performs nearly as well as the optimum scheme while requiring less communication bandwidth with a central processing node. We develop Ziv-Zakai bounds for TDE with partially coherent signals in order to study the achievability of the CRB. This analysis shows that a threshold value of coherence is required in order to achieve accurate time-delay estimates, and the threshold coherence value depends on the source signal bandwidth, the additive noise level, and the observation time. Results are included based on processing measured aeroacoustic data from ground vehicles to illustrate the frequency-dependent signal coherence and the TDE performance.     

Waveguide with resonant array inserts

The concept of guiding waves using passive arrays as frequency dependent walls is outlined. A prototype waveguide structure with arrays of tripoles as inserts has been built and used to demonstrate the wave guiding phenomenon.<>     

Mid-and far-IR focal plane arrays based on Hg1−x CdxTe photodiodes

This review presents the results of the research and development work carried out at the ORION RD&;P Center (Federal State Unitary Enterprise) on HgCdTe photodiodes and focal plane arrays based on solid solutions of mercury and cadmium tellurides for the 3–5 and 8–12 μm spectral ranges. The structure, topology, and parameters of the photodiodes and staring and time-delay-integration focal plane arrays, as well as the structure and circuitry of silicon multiplexers developed for the focal plane arrays, are discussed. The parameters of photodiode arrays of various formats and of a prototype thermal imager based on a 128 × 128 staring focal plane array are presented.