相控阵天线的设计与FDTD分析

基于工作频率在1.79 GHz的微带天线,首先研究了移相器的设计方法,然后利用两种不同方法实现的移相器,分别设计出了相控阵天线。通过FDTD进行建模和仿真实验,计算了相控阵天线在不同扫描角的远场辐射方向图,分析了实验误差,得出了结论,所设计的相控阵天线结构简约,主瓣尖锐,最大扫描角大于45°。     

基于P300的便携式中文输入系统

目前有关中文BCI输入系统的研究仅有拼音输入和笔画输入两种,且都克服不了中文输入速率较低、不便携等问题.据此提出了基于P300的五笔中文输入系统.此系统通过低成本OpenBCI套件,使用Wi-Fi协议传输脑电数据,在移动设备上实现刺激界面,并使用卷积神经网络处理脑电信号.实验表明,该系统具有高中文输入速率、高准确率以及...     

A flexible ultra-broadband multi-layered absorber working at 2 GHz–40 GHz printed by resistive ink

A flexible extra broadband metamaterial absorber(MMA) stacked with five layers working at 2 GHz–40 GHz is investigated. Each layer is composed of polyvinyl chloride(PVC), polyimide(PI), and a frequency selective surface(FSS),which is printed on PI using conductive ink. To investigate this absorber, both one-dimensional analogous circuit analysis and three-dimensional full-wave simulation based on a physical model are provided. Various crucial electromagnetic properties, such as absorption, effec...     

A flexible ultra-broadband metamaterial absorber working on whole K-bands with polarization-insensitive and wide-angle stability

For potential military applications, a flexible metamaterial absorber (MMA) working on whole K-bands with total-thickness of 3.367 mm, ultra-broadband, polarization-insensitive, and wide-angle stability is presented based on frequency-selective surface (FSS). The absorber is composed of polyvinyl chloride (PVC) layer, polyimide (PI) layer, and poly tetra fluoro ethylene (PTFE) layer, with a sandwich structure of PVC-PI-PTFE-metal plate. Periodic conductive patterns play a crucial role in the absorber, and in traditional, it is designed on the upper surface of PI layer to form LC resonance. Different from commonly absorber, all the patterns are located on the lower surface of the PI layer in this work, and hence the impedance matching and absorptivity are improved in this purposed absorber. The flexible absorber with patterns on lower surface of the PI layer is compared with that on upper surface of the PI layer, the difference and the reasons are explained by absorption mechanism based on equivalent circuit model, and surface current density and electric field distribution are used to analyze resonance peaks. Absorptivity is greater than 90% in a frequency range of 10.47 GHz-45.44 GHz with relative bandwidth of 125.1%, covering the whole Ku, K, Ka, and some of X, U bands, especially containing the whole K bands from 12 GHz to 40 GHz. Radar cross section (RCS) is reduced at least 10 dB in 11.48 GHz-43.87 GHz frequency ranges, and absorption remained about 90% when the incident angle changed from 0° to 55°. The purposed absorber is fabricated, measured, and experiment results show good agreement with theoretical analysis and numerical simulation. After bonded on outer surface of different cylinders with diameters of 200 mm and 100 mm, the absorption of MMA is approximately reduced 10% and 20% respectively, which shows good conformal character with surface of various curvatures. Due to the attractive performance on strong absorption in the whole K-bands, flexible and easy conformal, our design exhibits broad potential application in radar stealth and sensors.     

一种JMF数据源多路应用解决方案

基于Java开发的局域网(LAN)可视电话(会议)应用系统,具有跨平台等诸多优点,而JMF数据源多路应用是全面实现该系统的关键。本文给出了一种JMF数据源多路应用方案,实现客户端数据源的本地播放、局域网上多路传送和对发送视频的本地监视。方案的核心是正确运用了JMF数据源的克隆技术和恰当配置多路传送端口。该方案具有简单规范、稳定可靠的特点,完全满足基于JMF的局域网视频电话(会议)系统开发的需要。     

三维FDTD建模软件的开发及应用

介绍了三维FDTD建模软件的开发,电磁建模和网格生成采用Visual Basic实现。该软件提供给FDTD仿真软件诸如介质、网格、边界条件、激励源设置之类的数据文件;自动生成满足FDTD算法条件的均匀或非均匀网格。采用OpenGL技术,通过对图形的旋转、平移、缩放、透视等操作对目标物体进行细致的实时观察与修改,实现了计算区间内电磁场的动态变化演示,具有建模速度快、可视化效果好等优点,保证了FDTD数值求解过程的正确与高效。最后利用该软件对微带拐角等不连续性问题进行了建模和仿真,取得了较好的效果。     

PZT压电陶瓷极化工艺研究

介绍了6.5 MHz锆钛酸铅(PZT)压电陶瓷滤波器极化工艺的流程和基本原理,对极化电场、极化温度和极化时间等工艺参数进行了实验研究,并针对实验结果进行了理论分析,确定最佳的极化条件:极化电场强度为2.2 kV/mm、极化温度为130℃,极化时间为15 min。文章还对极化工艺中出现的其他一些问题进行了分析和探讨,从而有效地提高了压电陶瓷的压电性能指标。     

基于JMF的局域网视频电话(会议)系统开发

局域网（LAN）视频电话（会议）系统有广阔的应用前景,而基于Java实现的应用系统,具有跨平台等诸多优点.本文介绍了实际开发局域网视频电话（会议）系统的基本构成和主要功能,重点描述了服务器客户管理、系统通信控制和客户多媒体处理方案.该系统采用Java多媒体框架（JMF）类库和纯Java编程,界面友好、功能强大.     

低温氢化非晶硅薄膜晶体管研究

低温薄膜晶体管(TFT)的研究是开发大面积柔性衬底集成电路的基础.采用底栅TFT结构并入刻蚀阻挡层和钝化保护层,通过工艺参数和工艺流程的设计,研制了100℃低温氢化非晶硅TFT.实验对氢化非晶硅活性层、氮化硅介质层薄膜以及TFT特性进行了测试.所研制的低温TFT导通电流与截止电流之比高达106,场效应电子迁移率为0.825 cm2/Vs,表明适于柔性衬底工艺的100℃低温TFT得到了有效实现.     

粮食水份微波测量仪的系统设计

文章介绍了微波测量水份的基本原理和技术,详细阐述了粮食水份微波测量仪的系统设计以及利用单片机提高了仪器的智能化水平和整体性能。