Index sensing characteristics of the plasmonic sensor based on metal-insulator-metal waveguide-coupled structure

A plasmonic refractive index sensor based on metal-insulator-metal(MIM) waveguide-coupled structure is proposed and demonstrated in this paper.The physical mechanism of the device is deduced,and the finite difference time domain(FDTD) method is employed to simulate and study its index sensing characteristics.Both analytic and simulated results show that the resonant wavelength of the sensor has a linear relationship with the refractive index of material under sensing.Based on the relationship,the refractive index of the material can be obtained from the detection of the resonant wavelength.The results show that the sensitivity of the sensor can exceed 1600 nm/RIU,and it can be used in chemical and biological detections.     

A novel wide-band circular patch antenna

In order to overcome the narrow-bandwidth of the patch antenna, one kind of configuration which can widen the bandwidth significantly is discussed in this letter. Analyzed by the equivalent-circuits method and simulated by HFSS, a rule derived from simulated results that can aid to design the microstrip antennas is found. Finally, the structure parameters are optimized out, which reaches 44.67% impedance bandwidth. Furthermore, this kind of configuration can also be applied to the multi-layer patch antenna.     

ANTENNA ARRAY PATTERN NULL STEERING——A THEORETICAL INTRODUCTION

The antenna array pattern null steering is one of the important current topics in the array synthesistheory,due to it's very effectiveness to suppress the interfering signals.Thus in this paper the problemof forming nulls in the radiational pattern of three-dimensional arrays is discussed.This paper deals with the following aspects:The essential relations forming multi-nulls in thearrays are analysed by the method of vector space.A method forming multi-null regions is presentedin terms of the extensive property of null itself.The resolvent formulation of the radiational patternof multi-null steering is derived.The numerical results are given and discussed.The resolvent for-mulation is analogous to the one of the adaptive arrays.     

A novel structure in reducing the on-resistance of a VDMOS

A novel structure of a VDMOS in reducing on-resistance is proposed.With this structure,the specific on-resistance value of the VDMOS is reduced by 22%of that of the traditional VDMOS structure as the breakdown voltage maintained the same value in theory,and there is only one additional mask in processing the new structure VDMOS,which is easily fabricated.With the TCAD tool,one 200 V N-channel VDMOS with the new structure is analyzed,and simulated results show that a specific on-resistance value will reduce by 23%,and the value by 33% will be realized when the device is fabricated in three epitaxies and four buried layers.The novel structure can be widely used in the strip-gate VDMOS area.     

GENERATION OF SYMBOLIC NETWORK FUNCTIONS BY MODELING METHOD:AN IMPLEMENTATION

Algorithms and program structure of SFGEX,a program for generating symbolic networkfunctions,are introduced.The program is constructed by using the modeling method of the networkextension theory.In comparison with others,say the numerical interpolation method and thedeterminant evaluation method,the new method requires less operations and much less memoryspaces and its flexibility is incomparably good.In this paper,some algorithms integrated in SFGEXare described.A theorem for reference transformation of node impedance matrix,a least squaremethod for making division of two s-polynomials and a binary-array method for generation ofpartially symbolic network functions are used in the program.Finally,several topological rules fordeleting the redundant terms and repeated terms are given.     

An image magnification algorithm using the GVF constraint model

An image magnification method with a Gradient Vector Flow（GVF）constraint-based anisotropic diffusion model is proposed in this letter.A Low-Resolution（LR）image is first magnified using bilinear interpolation,and then an iterative image restoration method,with the use of an anisotropic diffusion model and a Gaussian moving-average constraint,is applied to the magnified image.The estimated GVF of a High-Resolution（HR）image can be used to remove the jagged effect and to preserve the textural structure in the image.Meanwhile,the use of the Gaussian moving-average LR model can provide a data fidelity constraint,which renders a magnified image closer to the ideal HR version.Experimental results show that the proposed method can improve the quality of magnified images in terms of both objective and subjective criteria.     

The On-line Calibration Technology of System Delay Based on Dynamic Delay Cancellation for Generalized TT＆C Channel Simulator

An on-line system delay calibration method based on dynamic cancellation for generalized high-precision Tracking, telemetry and command （TT＆C） channel simulator is proposed. This method manages to estimate the time-varying system delay in real time through the coupling signal of input signal and simulated output signal, and then modifies the simulated parameters by the estimated value. With this method, it effectively avoids the effect of time-varying system delay caused by temperature drift, aging of components and other factors on high precision simulation. In this paper, the dynamic cancellation technology, which is the kernel and foundation of this method, is presented to eliminate the simulated motion law between the input signal and output signal. The time delay estimation method based on cross correlation and area barycenter arithmetic is introduced to estimate the time-varying system delay. The simulation results show the validity and high-precision performance.     

RECOGNITION OF MODULATION SYSTEM IN COMMUNICATION

Recognition of modulation system is an important problem in the modern electronicreconnaissance.A general method for solving this problem is suggested in this paper.From asegment of a captured signal we can determine the modulation system and extract its parameterwith this method.The theoretical basis,algorithms and test results of this method are described.It has been proved that the method is very effective in practical situation.     

一种应用于自组织网络的动态节点划分算法(英文)

A dynamic nodes partition algorithm for the Ad Hoc network is proposed. Firstly, Roam cluster method is used to cluster 926 random nodes in a square region. Subsequently, the central moving model based on the simulated annealing algorithm and the least circle overlay model is constructed to remove the network redundancy of the circle number and circle radius respectively. Simulation results show that the algorithm can effectively maintain the stability of network structure and increase balancing capabilitie...     

引入悬浮栅对有机薄膜晶体管的阈值电压进行调整

The structure of organic thin film transistors (OTFTs) is optimized by introducing floating gate into the gate dielectric to reduce the threshold voltage of OTFTs in this article. Then the optimized device is simulated and the results of the simulation show the threshold voltage of optimized device is reduced by about 10 V. The reduction of the threshold voltage is helpful and useful for the application of OTFTs in many areas. In addition, this way to reduce threshold voltage of OTFT is compatible with traditional silicon technology and can be used in manufacture.     

A three-dimensional horizontally wide-angle noniterative beam-propagation method based on the alternating-direction implicit scheme

A three-dimensional horizontally wide-angle beam-propagation method is proposed on the basis of the alternating-direction implicit scheme, in which the Pade/spl acute/ approximant is applied only to the horizontal direction. The present formulation reduces the splitting error to the first order without an iteration procedure. The effectiveness is demonstrated through the wide-angle propagating beam analysis of a tilted optical waveguide.     

Apexes-linked circle gratings for low-loss waveguide bends

A low-loss waveguide bend with two apexes-linked circle gratings based on the concept of multiple phase compensation is designed. The apexes-linked circle gratings not only compensate the phase-difference in the bend corner, but also avoid distorting the eigenmode. Simulation results predict that the phase front of the modal field can be tilted correctly in the wide-angle waveguide bend. The transmitted power efficiency can be as high as 89% for bending angle up to 10°     

Quasi-3-D simulation of high-brightness tapered lasers

We present a simulation tool useful to optimize the design of semiconductor tapered lasers and to study the physical processes inside of them. This is achieved by using a state-of-the-art quasi-three-dimensional (quasi-3-D) electrical and thermal model, coupled to a two-dimensional (2-D) wide-angle beam propagation method optical model. A calibration procedure of model parameters is proposed to contribute to the development of reliable simulation tools. Different laser diodes with a tapered gain section, emitting at 735 and 975 nm, are used to validate the model through the extensive comparison of experimental and simulated results. The suitability of 2-D and 3-D electrical, thermal, and optical models is discussed in terms accuracy and computational effort.     

宽角抛物方程在阻抗边界条件下的应用

对抛物方程中的伪差分算子进行Feit-Fleck宽角近似处理,分析了这种近似所带来的误差;详细阐述了阻抗边界条件下求解这种宽角抛物方程的分步傅立叶变换方法,并以此计算了海平面上电波传播情况,与窄角抛物方程及几何光学双射线模型的计算结果进行比较,说明了这种宽角抛物方程在阻抗边界条件下计算较大仰角电波传播问题是可行的.     

宽带宽角圆极化贴片天线的实验研究

本文提出一种新的宽带宽角圆极化微带天线设计方法,在利用容性探针近耦合馈电的基础上,通过平衡馈电,使贴片天线的阻抗带宽(VSWR≤2)和宽角轴比带宽(45°圆锥空域内的AR≤3dB)达到20%以上.实验测试表明,利用该方法设计的贴片天线的带宽达到26.33%(VSWR、宽角AR同时满足要求),从而证实了该方法的正确性和实用性.     

一种宽带宽角双极化相控阵天线单元研究

设计了一种宽带宽角双极化相控阵天线单元,该天线单元采用指数渐变开槽天线形式,并设计了金属匹配柱安装在双极化天线单元之间,保证了开槽天线的接地连续问题。依次给出了该双极化天线单元的仿真设计、阵列样机的性能测试,从仿真和测试结果中可以看出,该双极化天线在3倍频程带宽内具有良好的匹配和辐射特性,并且能实现大角度二维扫描。该双极化天线单元具有宽频带、体积小、结构简单等特点,适于用作宽带宽角扫描相控阵天线的阵列单元。     

X 波段宽带宽角扫描相控阵天线的设计

设计了一种X波段宽带宽角扫描相控阵雷达系统的小型阵列天线,该天线采用Vivaldi 天线做为阵列单元。在考虑阵列单元间的互耦效应下,仿真设计了9*9 小型阵列天线,使该阵列天线在相对带宽达40%下的有源驻波系数小于2,其有源单元方向图E面、H面的波瓣宽度分别达到120度、110度以上。对9*9天线阵的实物进行了加工与测试,测试结果说明了该阵列天线具有良好的宽带宽角扫描特性。因该天线结构简单,重量轻,在相控阵雷达天线中有很大的应用价值。     

Efficient nonuniform schemes for paraxial and wide-anglefinite-difference beam propagation methods

Efficient nonuniform schemes, based on the generalized Douglas (GD) scheme, are developed for the finite-difference beam propagation method (FD-BPM). For a two-dimensional (2-D) problem, two methods are presented: a computational space method and a physical space method. In the former, the GD scheme is employed, after replacing a nonuniform grid in the physical space with a uniform one in the computational space. In the latter, the GD scheme is directly extended to a nonuniform grid in the physical space. We apply these two methods to paraxial and wide-angle FD-BPM's. The fourth-order accuracy is achieved in the transverse direction, provided that the grid growth factor between two adjacent grids is r=1+O(Δx). For the paraxial BPM, the reduction in the truncation error is demonstrated through modal calculations of a graded-index waveguide using an imaginary distance procedure. For the wide-angle BPM, the propagating field in a tilted waveguide is analyzed to show the effectiveness of the present scheme. As an application of the physical space method, an adaptive grid is introduced into the multistep method     

宽角扫描侧馈偏置卡塞格伦天线的优化设计

为满足星载天线空间电扫描的要求,研究了宽角扫描侧馈偏置卡塞格伦天线(SFOC)的设计问题.给出了SFOC天线的结构形式,通过射线追踪的方法对SFOC的最佳馈源位置和最佳馈源指向进行了优化设计.二者的确定不仅改善了SFOC天线系统的扫描特性,而且提高了它的工程可实现性.分析结果表明,该SFOC天线在宽角扫描过程中,方向图畸变很小,增益损失和副瓣电平均达到了设计要求,从而为全球扫描星载天线的设计提供了有效的方案.     

基于计算全息的斜面和曲面光刻

斜面和曲面微结构元件在微电子学、微光学、微流体学等领域有着重要的应用,为了实现快速、低成本的斜面和曲面光刻,提出了利用基于液晶空间光调制器的纯相位计算全息技术投影目标图案到斜面和曲面进行曝光的方法。生成了斜面和球面全息光场,对光场进行消散斑和杂散光去除的处理,完成了斜面和球面光刻实验验证。实验结果表明:该方法加工效率高、设计灵活多变,不受单一结构限制,是一种极具潜力的三维微纳加工方法。