宽带超低相位噪声测量系统设计与实现

随着频率源技术的不断发展,信号的频段范围和相噪水平不断提升和优化,这对相位噪声的准确测量提出了新的挑战。文章针对雷达探测、精确制导、时频基准等微波射频领域中高性能低噪声频率源相位噪声指标的测试需求,对鉴相法测量相位噪声的原理进行了分析研究,设计了低噪底的鉴相通路。同时结合互相关技术和微波变频等技术,设计了具有双鉴相通道的互相关式相位噪声测量系统,进一步优化系统噪底,从而实现宽带超低相位噪声信号指标的准确测量。     

智能仪器在无线通信测试测量中的应用

智能仪器仪表技术在无线通信系统领域有着重要作用.文章从无线通信系统中的测量参数概念入手,结合3G、LTE等方面的相关测试参数讨论了无线通信系统测量测试中的仪器原理和基本应用,探讨了智能仪器的发展方向和应用前景.     

在片微波参数测量系统计量技术进展

在片微波参数测量系统主要通过探针台建立微波仪器与半导体裸芯片之间的信号连接通道,从而测量半导体裸芯片的微波参数。在片微波参数测量系统对提升芯片的性能,控制质量,保证芯片的一致性和稳定性方面具有重要的意义。国外相关的计量技术与测量系统同步发展,我国由于半导体产业起步较晚,测试系统大多采用进口,相关计量测试技术在过去很长一段时间发展相对缓慢。最近10 年我国奋起直追,不断缩小与世界先进水平的差距,目前已经完成40 GHz 以内的主要在片微波参数测量系统计量能力。文中回顾了本领域的技术发展历程,介绍国内外技术发展特点,对于进一步发展相关计量技术具有指导意义。     

基于天线测试系统的简易扩频设计及应用

基于通用天线近远场测试系统,给出了系统扩频设计和工程应用的思路,并分别对扩频系统的本振相参、上下变频的一致性进行了论述。实现了Ka频段以下的平面近场、远场天线测量系统的扩频与应用,并给出了8单元EHF频段阵列天线在不同测试系统下的天线测试方向图。测试结果表明,经扩频的测试系统方向图测量数据与毫米波天线测试系统直接测量的结果吻合,说明扩频系统能够满足毫米波天线方向图的测试需求,并具有较高的测试精度,且设计成本较低。同时还具有一定的通用型,对天线的毫米波扩展测试具有较好的工程应用价值。     

小型化数字测频接收机

本文介绍了AD公司的RF/IF相位和幅度测量芯片AD8302,并以此芯片为核心,组合功分器、延迟线和FPGA芯片设计了瞬时测频接收机,改进了传统的设计方案.依照设计制作了测频系统,并对系统整体性能进行了测试,测试结果表明本系统可以准确测量1.4～2.0 GHz范围内的信号,测频精度为10 MHz.     

霍耳效应测试系统

本文介绍了全自动“霍耳效应测试系统”的基本构成,并对每个分系统作了较为详细地描述。本系统具有测量样品类型全、数量多、测试速度快、测量和控制软件功能全、使用方便等特点。     

基于双通信接口的多通道信号源设计

针对飞行器测试领域中信号源系统通信接口单一的问题,设计了一种基于PCI总线和以太网的多通道信号源系统。信号源以FPGA为中控单元,能通过PCI总线接口或以太网接口与上位机进行通信,可输出多路直流信号、数字量串口信号（RS485信号和RS422信号）、指令信号和交流信号。实际测试结果表明,本设计可满足测量系统信号要求,可扩展性、通用性较强,已成功应用于某航天测试系统。     

微计算机在微波测量中的应用

本文综述微计算机在微波测量和仪表领域中的应用。这方面的应用也称之为计算机辅助微波测量技术。主要内容包括智能化仪表和自动化测试系统两方面,并以时域反射仪(TDR)和双六端口自动化网络分析仪(DSPNA)中的仪表组成和微机应用为例来介绍现代化自动化测试系统。本文表明,微计算机用于微波测量将带来高测试精度、系统组成灵活、全自动化、更低的代价等好处。     

可用带宽测量算法的改进

网络测试是及时了解网络运行状态、检测网络拥塞、提供接入控制参考依据以及保证网络服务质量的基础和必要手段。带宽测量属于网络的系统测试范畴,其相关测量算法一直是网络测试领域的研究热点和难题。文章在重点讨论可用带宽测量技术的基础上,对可用带宽测量工具Pathload进行了改进,实际测量结果表明改进算法在测量准确性等方面改善了测量效果。     

基于物联网的实验设备管理系统的研制

本文设计了一种基于物联网的实验设备智能管理系统总体方案,搭建了硬件平台并设计实现了各软件模块。本系统采用ZigBee技术以及RFID技术模拟实现了校园实验室实验设备的入库、借出、查询和归还等功能。测试结果表明,与物联网技术相结合的智能物流管理系统能够高效、实时地对物流管理各个流程进行优化。本系统亦可以扩展到图书管理,超市货物管理等相关领域。     

Nonlinear characterization of GaN HEMT

DC I-V output, small signal and an extensive large signal characterization (load-pull measurements) of a GaN HEMT on a SiC substrate with different gate widths of 100μm and 1 mm have been carried out. From the small signal data, it has been found that the cutoff frequencies increase with gate width varying from 100μm to 1 mm, owing to the reduced contribution of the parasitic effect. The devices investigated with different gate widths are enough to work in the C band and X band. The large signal measurements include the load-pull measurements and power sweep measurements at the C band (5.5 GHz) and X band (8 GHz). When biasing the gate voltage in class AB and selecting the source impedance, the optimum load impedances seen from the device for output power and PAE were localized in the load-pull map. The results of a power sweep at an 8 GHz biased various drain voltage demonstrate that a GaN HEMT on a SiC substrate has good thermal conductivity and a high breakdown voltage, and the CW power density of 10.16 W/mm was obtained. From the results of the power sweep measurement at 5.5 GHz with different gate widths, the actual scaling rules and heat effect on the large periphery device were analyzed, although the effects are not serious.The measurement results and analyses prove that a GaN HEMT on a SiC substrate is an ideal candidate for high-power amplifier design.     

6.0-6.4GHz室内MIMO无线信道测量与传播特性分析

工作在6GHz以上高频段的多输入多输出(Multi-Input-Multi-Output,MIMO)无线通信系统是下一代无线移动通信的有力竞争方案.目前,对制约无线系统性能的高频段空时无线信道特性研究仍较少见.针对这一现状,采用基于网络分析仪的信道测量平台对典型办公环境下6.0-6.4GHz MIMO无线信道特性进行测量和分析.为了明确高频段为系统设计带来的新问题,将测量得到的高频段MIMO信道特性参数与低频段对比.对比结果表明,6.2GHz频段与2.45GHz频段MIMO信道传播特性存在较大差异.在对6.0-6.4GHz室内覆盖MIMO无线通信系统进行设计和评估时,需要基于6.0-6.4GHz频段无线信道传播的新特性对系统的关键技术和方案进行调整.     

大型紧缩场电气性能检测

介绍了大型紧缩场电气性能检测的原理、系统和方法，解决了其中的关键技术问题，对紧缩场系统的后期应用，如天线测试、RCS测试等，有重要参考和借鉴意义。     

大型天线表面精度实时检测

介绍一种大型天线表面精度实时检测仪,它可以检测出天线表面形变的位置和大小,通过实时调整天线面板,从而大大改善大型反射面天线的系统性能。     

Design and Analysis of Triple-Band Rectangular Microstrip Antenna Loaded with Notches and Slots for Wireless Applications

In this paper, a rectangular triple-band microstrip antenna has been designed for Bluetooth application by successively loading notches and slots of different dimension in radiating patch. The conventional microstrip antenna suffers with narrow impedance bandwidth. The current work affords an alternate option to enhance the bandwidth of antenna that resonates in triple-band operation. Initially, the antenna is resonating in single-band but after loading slots, the bandwidth of microstrip antenna has been obtained 1.97% (lower band), 10.35% (middle band) and 33.16% (upper band) resonating in triple-band with three resonant frequency at 1.422 GHz (lower resonant frequency), 1.791 GHz (middle resonant frequency) and 2.467 GHz (higher resonant frequency). The suggested antenna has upper frequency band in the range of 2.045–2.858 GHz resonating at 2.467 GHz frequency and it is appropriate for Bluetooth applications (2.40–2.48 GHz) and both lower band useful for other wireless (L-band) applications. The return loss of upper band is ??34.52 dB at 2.467 GHz. The suggested microstrip antenna is directly fed by 50 ohm microstrip line feed. The suggested antenna has been designed, simulated and analyzed by IE3D simulation software.

     

Dual-band UWB bandpass filter with triangular DB-DGS for WLAN applications in DSRC band

A dual-band Ultra-wideband (UWB) bandpass microstrip filter with triangular dumbbell shaped defected ground structure (DB-DGS) for wireless local area network applications in DSRC band is proposed in this article. The proposed dual-band filter has center frequencies at 2.67 GHz and 4.68 GHz, return loss obtained is −33.40 dB and −16.55 dB respectively, wide bandwidth of 1.21 GHz (26%), pass band between 2.14 GHz and 6.44 GHz and high gain of 10.30 dB which makes it suitable for modern applications in dedicated short range communication operating in 5.8 GHz band. To further validate the design concept, a microstrip UWB filter is designed, fabricated and tested. Comparison is made among circular, square and triangular dumbbell shaped DGS on the basis of scattering parameters and bandwidth, in which triangular shaped DB-DGS outperforms the other two. Further, parametric analysis of triangular DB-DGS has been performed and comparison is made with filters of similar nature. Experimental results are in good agreement with simulations. The fabricated filter is compact in size, has low insertion loss, exhibits high selectivity and demonstrates excellent out of-band performance.     

1GHz微波功率MOSFET的研究

分析了影响ＶＤＭＯＳ器件频率性能的一些关键参数,研制出１ＧＨｚ输出功率１０Ｗ,增益８ｄＢ的ＶＤＭＯＳ器件,验证了ＶＤＭＯＳ器件在这一频段的工作性能,测试结果与设计指标和理论计算基本符合,说明理论分析准确,工艺过程控制较好。     

Design and Development of Thermistor based Power Meter at 140 GHz Frequency Band

Design and development of thermistor based power meter at 140 gigahertz (GHz) frequency band have been presented. Power meter comprises power sensor, amplifier circuit and dialog based graphical user interface in visual C++ for the average power measurement. The output power level of a component or system is very critical design factor. Thus there was a need of a power meter for the development of millimeter wave components at 140 GHz frequency band. Power sensor has been designed and developed using NTC (Negative Temperature Coefficient) thermistors. The design aims at developing a direct, simple and inexpensive power meter that can be used to measure absolute power at 140 GHz frequency band. Due to absorption of 140 GHz frequencies, resistance of thermistor changes to a new value. This change in resistance of thermistor can be converted to a dc voltage change and amplified voltage change can be fed to computer through data acquisition card. Dialog based graphical user interface (GUI) has been developed in visual C++ language for average power measurement in dBm. WR6 standard rectangular waveguide is the input port for the sensor of power meter. Temperature compensation has been achieved. Moderate sensor return loss greater than 20 dB has been found over the frequency range 110 to 170 GHz. The response time of the power sensor is 10 second. Average power accuracy is better than ±0.25 dB within the power range from −10 to 10 dBm at 140 GHz frequency band.     

Microwave absorption properties of gold nanoparticle doped polymers

This paper presents a method for characterizing microwave absorption properties of gold nanoparticle doped polymers. The method is based on on-wafer measurements at the frequencies from 0.5 GHz to 20 GHz. The on-wafer measurement method makes it possible to characterize electromagnetic (EM) property of small volume samples. The epoxy based SU8 polymer and SU8 doped with gold nanoparticles are chosen as the samples under test. Two types of microwave test devices are designed for exciting the samples through electrical coupling and magnetic coupling, respectively. Measurement results demonstrate that the nanocomposites absorb a certain amount of microwave energy due to gold nanoparticles. Higher nanoparticle concentration results in more significant absorption effect.