阻抗匹配电路在滤波器测试中的应用

为解决扫频仪日趋老化带来的某型非标准阻抗滤波器测试问题,通过设计阻抗转换器实现了用网络分析仪对滤波器的测试。介绍了扫频仪与网络分析仪的测试原理和它们之间的区别,阐述了网络分析仪HPE5100B替代扫频仪JW1252W测试滤波器的实现方法,以及阻抗匹配电路的原理及其在滤波器测试中的应用。实验证明,用网络测试仪测试数值一致性好、操作简单、精度高、减少了工作量、降低了成本。     

基于LPC2378的天调匹配性能检测仪的设计及实现

为了解决生产中短波天调配谐过程存在的劳动强度大,统计不够准确等问题,设计了一种检测仪。该检测仪以嵌入式技术为基础,利用短波电台所提供的遥控命令,实现短波天调自动配谐功能,并根据统计得到的配谐数据判断天调匹配性能是否合格。经生产验证,该测试仪在提高劳动效率的同时,还能减少人工统计数据可能带来的误差。     

基于环流反馈的逆变器并联系统仿真分析

对于逆变器并联系统,各模块输出电压之间如若存在幅度和相位上的差异,势必会产生在模块间流动的环流。文中在逆变器并联系统环流产生机理分析的基础上,对是否加入环流反馈时系统的阻抗和稳定性进行了分析,证明采用环流反馈可以增大系统环流阻抗,在保持输出电压不变的前提下有效地减小了环流,最后通过Simulink仿真证明此方式的有效性。     

基于双同轴阶跃阻抗谐振器的带通腔体滤波器的设计

介绍了一种减小腔体滤波器体积的设计方法。分析了双同轴阶跃阻抗谐振器的谐振条件和未加载Q值,依据滤波器理论和运用HFSS软件设计了一个基于双同轴阶跃阻抗谐振器的带通腔体滤波器。在3.7～3.9 GHz的频带内,该滤波器插入损耗小于0.5 dB,回波损耗大于20 dB,测试与仿真结果相吻合。该滤波器具有体积小、结构简单易于加工等优点。     

发射机的电磁兼容性设计

EMI（电磁干扰）问题的深入研究对提高所设计产品的可靠性有着较大的现实意义。文中阐述了EMC（电磁兼容性）在电路设计中的重要性和电子设备的EMC问题。就雷达发射机的EMC设计问题,根据发射机干扰信号的传播途径和耦合方式,针对经常出现的各种EMI问题,提出了接地、屏蔽、滤波、瞬态抑制等4种抑制EMI的方法。介绍了其他一些常用的提高设备EMC的方法,分别从PCB（印制电路板）设计、设备内的布线、软件抗干扰设计等方面进行了探讨。     

A Novel Buffering Technique for Aqueous Processing of Zinc Oxide Nanostructures and Interfaces,and Corresponding Improvement of Electrodeposited ZnO‐Cu2O Photovoltaics

A novel buffering method is presented to improve the stability of zinc oxide processed in aqueous solutions. By buffering the aqueous solution with a suitable quantity of sacrificial zinc species, the dissolution of functional zinc oxide structures and the formation of unwanted impurities can be prevented. The method is demonstrated for ZnO films and nanowires processed in aqueous solutions used for the selective etching of mesoporous anodic alumina templates and the electrochemical deposition of Cu₂O. In both cases, improved ZnO stability is observed with the buffering method. ZnO‐Cu₂O heterojunction solar cells (bilayer and nanowire cells) synthesized using both traditional and buffered deposition methods are characterized by impedance spectroscopy and solar simulation measurements. Buffering the Cu₂O deposition solution is found to reduce unwanted recombination at the heterojunction and improve the photovoltaic performance.     

Necessary and Sufficient Stability Criterion and New Forbidden Region for Load Impedance Specification

A necessary and sufficient impedance stability criterion for the DC Distributed power system （DPS） is proposed in small-signal sense, which has no conservativeness when compared with other stability criteria. This paper discusses the stability margin and gives it a definition for the round forbidden region. The reasons why the stability margin varies at different interfaces are also discussed in this paper. With the impedance stability criterion and stability margins considered, the sector forbidden region, which is a new forbidden region and can be easily calculated in the Bode diagram, is proposed to solve the calculation problem of the round forbidden region in engineering application. This paper also provides examples and simulations to verify the necessary and sufficient impedance stability criterion and the proposed sector forbidden region for the load impedance specification.     

“直流接地查找设备”对保护误动的分析

变电站直流系统接地会导致继电保护的误动作,对电网的可靠性运行危害极大。当发生直流接地时,为了快速、准确地找到接地点,除了常规的直流拉路排除法外,最普遍的方法就是使用＂直流接地查找设备＂对各个直流回路进行排查,找到并消除接地点。但＂直流接地查找设备＂的原理及工艺不一,有可能在接地查找过程中发生继电保护误动的现象。本文就＂直流接地查找设备＂的工况,对现场发生实际接地的各种状态量进行分析,研究发生保护误动作的原因,并提出使用＂直流接地查找设备＂的工作流程。     

电子电路中抗EMI设计

电磁干扰(EMI)可分为传导干扰和辐射干扰,消除干扰的方法可以采用硬件方法和软件方法,硬件方法主要有屏蔽、接地、隔离和滤波等,而软件方法主要是滤波。笔者对各种方法进行总结,并指出各种方法所存在的问题以及适用场合,并对一些常用方法提出改进措施。     

Bandwidth Aspects in Second Generation Current Conveyors

This paper discusses bandwidth problems associated with second-generation current conveyors (CCII). In particular, our work is centered in high-capacitance applications, and has been oriented for wireless optical links and applied physics. We discuss techniques for improving bandwidth in these CCIIs, and develop a new CCII structure with larger bandwidth than traditional circuits. These circuits are then compared in terms of their noise and dynamic range characteristics. A test circuit was developed to verify these different bandwidth behaviors.