960MHz同轴介质谐振器滤波器的研制

研制了用四个高Q值介质同轴谐振器构成的带通滤波器,谐振器之间的耦合通过陶瓷基片上的电容实现,讨论了影响谐振器插入损耗的主要因素。结果表明,该四级式低损耗介质同轴谐振器滤波器中心频率f0为960MHz,插入损耗小于3.0dB,能满足设计要求。     

High temperature dielectric properties measurement system at 915 MHz based on deep learning

A ridged waveguide and heating system based on deep learning for dynamic measurement of dielectric properties at high temperatures has been developed. Firstly, specially designed ridged waveguide at the frequency of 915 MHz was utilized. The finite difference time domain simulation was then combined with the deep learning algorithm to construct the dielectric properties. In addition, the calibration method based on a two‐point algorithm was involved in the network. The precision of the measured dielectric constant and loss tangent was improved by 4.4% and 1.9%, respectively. Simulated results indicated that the deep learning algorithm had higher accuracy than back propagation neural networks and support vector machine algorithms. The reliability of the system was verified by Si₃N₄ and alcohols at room temperature. The dielectric properties of quartz particles were also tested over a temperature range up to 900°C. The experiment results agreed well with the reference values. This system can measure a wider range of dielectric properties and achieve higher accuracy using the advanced deep learning algorithm. It is more convenient to measure large size materials in industrial applications at high temperatures.     

基于GSM网络的智能电子锁芯无线报警系统

基于智能电子锁芯的编码地址和315 MHz的无线数据传输,利用STC12LE5A60S2单片机和GSM SIM900A模块设计了一种无线报警系统.介绍了无线报警系统的基本工作原理,给出了硬件结构图和软件设计流程,并对锁芯的无线数据收发技术和GSM网络的AT控制技术及计算机数据管理技术进行了深入阐述.对系统的软硬件实验测试结果证明,该系统能够进行智能锁芯地址的对码和报警电话的预置,能在无障碍的情况下准确接收半径为20 m的范围内电子锁芯发出的无线信号中所包含的实时报警信息,实现和预置手机的电话与短信报警功能,并实现报警记录数据的计算机查询和数据库处理,是一种适用于公司和家庭的局域智能化报警技术.     

超短波电波传播路径损耗中值公式的数值实验建模

在超短波30~88 MHz波段,路径损耗中值公式Okumura-Hata模型已远远不能满足实际工程对损耗计算的高精度需求,本文利用电磁数值仿真方法,建立真实城市环境中的电波传播模型,通过大量的多种背景模型和收发条件下的数值实验,拟合出适用于30~88 MHz波段的电波传播路径损耗中值公式,弥补Okumura-Hata公式在低端频段的空缺,有效地扩展了Okumura-Hata公式的应用范围,提高了它的实用性。     

An efficient Sm and Ge co-doped ceria nanocomposite electrolyte for low temperature solid oxide fuel cells

In this study we present a new nanocomposite electrolyte based on samarium (Sm) and germanium (Ge) co-doped ceria Ce_0.7Sm_0.15Ge_0.15O_2-δ (SGeDC). The nanocomposite electrolyte was prepared using co-precipitation method. The crystal structure and surface morphology were determined using x-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. Four probe dc conductivity indicated the value of 0.074 S/cm at 650 °C. The Fuel cell performance was carried out using hydrogen as fuel. The maximum OCV observed was 0.95 V while the peak power density came out to be 600 mW/cm² at 600 °C. It is suggested that adding Ge, the conductivity as well as performance of this new nanocomposite electrolyte is comparatively enhanced and it can find potential applications in low temperature solid oxide Fuel cells (LTSOFCs).     

一种三频内置手机天线的设计与仿真

本文提出一种新型平面倒置F型三频手机天线(PIFA)。天线采取单馈点同轴馈电,上层辐射片开h形槽孔,应用时域有限差分法对天线进行设计和仿真,在GSM900MHz,DCS1800MHz和ISM2450MHz 3个频段的增益分别达到了0.1dBi,0.25dBi和0.4dBi,带宽分别达到了6.44%,6.67%和4.5%,表明该天线可在三个频段工作,满足了新一代无线通信系统对频段、带宽和增益的要求。     

任意频点双混频时差测量方法及仪器的研究

介绍了采用双混频时差法研制的任意频点比对测量系统,媒介频标采用DDS代替了传统的调偏振荡器,采用双混频时差法原理,研发一种1~30 MHz频率范围内任意频点的时差、频差比对分析系统。系统比对测量频率1~30MHz,采样时间100 ms~106s;本底噪声(1 s)为5MHz/10MHz优于5×10-13,其他频点优于1×10-12。测量系统通过软件算法可以测量稳定度、准确度、相位差、老化率。     

1.4GHz频段IMT系统与其他业务共存分析及干扰规避措施建议

1 427~1 518 MHz频段具有良好的传播特性,且有利于IMT系统部署,该频段已成为2015年世界无线电大会(WRC15)AI.1议题IMT候选频段的研究热点。本文以未来在1 427~1 518 MHz频段内部署IMT系统为前提,对IMT系统与1 427~1 518 MHz频段内同频的航空遥测(AMT)业务以邻频的卫星移动(MSS)业务开展兼容性分析,通过确定性分析以及Monte Carlo仿真方法得到了共存所需要的隔离度要求,结合预留一定保护带、空间隔离距离以及限制IMT系统带外发射限值等手段,证实IMT与已有业务能够实现无干扰共存。     

915 MHz微波在沥青路面再生加热中的应用

为验证915 MHz微波频率用于沥青路面再生加热的可行性,在分析微波加热机理的基础上,设计了喇叭天线参数并对其进行了优化,采用CST仿真软件,进行了915 MHz与2 450 MHz两种微波频率下单天线与阵列天线对沥青混合料的加热效果对比,同时对不同天线间距、加热高度、混合料厚度等对加热效果的影响因素进行了仿真分析。结果表明:915 MHz微波频率加热沥青混合料具有更好的均匀性与深度方向上更小的温度梯度;改变天线间距、加热高度和混合料厚度,会导致加热箱内微波相互干涉现象发生变化,进而对加热效果产生影响,当混合料厚度为250 mm,天线间距为70 mm×70 mm,加热高度为70 mm,此时加热效果最好,混合料温度均值最高,且离散系数最低,温度均匀性好,沥青老化现象较少。对于大型微波再生加热设备,由于其要求加热厚度大、产量高,采用915 MHz更为合适。     

无中心选址对讲机的特点与前景

论述了移动通信组网不一定要有中心,对有中心组网与无中心组网作了对比,介绍了无中心组网设备的关键技术、无中心选址对讲机的特点与前景.