微波锁相振荡器的相位噪声及其测量

现代一些电子技术(如空间通信等)都需要一个频谱极纯,也即相位噪声极低的微波信号源。一些文献已证实,锁相振荡是改善相位噪声的有效措施。本文讨论了微波锁相振荡器相位噪声的一些特性,包括:相位噪声与锁相环电路方式的关系、最佳噪声带宽的推导、信号射频谱与相位噪声谱的关系等;详细讨论了相位噪声的测量方法(射频频谱法),并对五种C波段微波源相位噪声的测量结果,进行了分析和讨论。     

频谱分析仪的原理和发展

频谱分析仪对射频工程师来说是必不可少的测试工具。然而各种频谱分析仪实现方法不尽相同，如带通滤波器频谱分析仪、中频滤波器频谱仪和FFT频谱仪。本文着重阐述频谱分析仪的实现原理和发展阶段．并在参数说明中对分辨带宽和视频带宽对测量显示结果的影响加以分析．并且对两种不同的频谱分析仪在各性能参数上进行了分析比较。最后对面向通讯领域的新一代频谱分析仪做了介绍。     

频谱仪快速测定窄线宽激光器线宽

针对传统光谱仪和F-P 干涉仪分辨率不能满足窄线宽激光器线宽的测量要求, 基于延时自外差法搭建测试平台.设置频谱分析仪分辨率参数抑制噪声实验, 通过使用20 km 延时光纤、80 MHz声光移频器和50:50 光纤耦合器, 通过光电探测器实现光电转换并利用频谱分析仪分析测试信号.对频谱分析仪分辨带宽RBW 和视觉带宽VBW 以及扫频范围(Scan Range)进行优化设置, 在不降低测试灵敏度的情况下, 将重叠信号分辨开, 使其不会过多滤掉高频成分而失真并对线宽功率谱峰值进行洛伦兹曲线拟合.最后得到了1 550 nm 波长可调谐光纤激光器(1 520~1 570 nm)的线宽值约为161 kHz, 为频谱仪的参数优化设置及窄线宽激光器线宽标定提供了相关参考.     

罗德与施瓦茨全面的微波毫米波测量解决方案

罗德与施瓦茨（R＆S）公司在2012年9月天线与微波展览会上,全面展示的高达500 GHz的微波毫米波测试仪表和解决方案,其中包括频谱仪,信号源,网络分析仪,功率计,示波器：·在射频性能和带宽方面表现优异的高端频谱分析仪R＆S FSW;·创新的实时频谱分析仪R＆S FSVR。     

40GHz全自动频谱分析仪

1964年HP公司首次开发成功半自动频谱分析仪,这是由显示单元和射频单元两个机箱组成的台式设备。六十年代的频谱分析仪实质上是一种模拟调频接收机,在微波波段依靠调节谐振腔长度来变换频率,更换插件来扩充带宽。当时微处理器尚未出现,频率合成技术和GPIB总线更是七十年代以后的技术,HP公司的半自动频谱分析仪代表六十年代的最高水平,而且HP公司一直     

利用泰克公司NetTek分析仪解决移动网络干扰问题(Ⅲ)

三、测试移动射频干扰的手段泰克公司NetTek分析仪泰克公司NetTek分析仪加装频谱与干扰分析选件，具有操作简便，便携坚固，电池供电(一块锂电池可测试4小时，2块8小时适于外场作业的特性。灵敏度高，易于发现干扰；具有干扰带宽测试功能，与频谱分析功能配合，可对干扰性质进行详细分析;干扰噪声电平测试功能，完全针对不同移动通信体制，适于干扰定量分析音频场强相关功能使NetTek具有超强的干扰定位能力。下面详细介绍NetTek分析仪在干扰测试方面的功能。频谱分析—频谱分析是干扰测试的基础，是干扰发现、干扰定性，特别是互调干扰…     

频谱分析仪在卫星地球站运用中的注意事项

频谱分析仪是把信号能量作为频率的函数显示出来的测量仪器,用示波器作为显示器描绘出信号幅度与频率间的函数关系图形。在射频技术领域中,该仪器发挥着举足轻重的作用。在卫星地球站,频谱分析仪也发挥着举足轻重的作用。作为测试仪器,它可以进行多种射频功能的测试,如测量功率放大器的带宽、幅频特性、带内外杂散、噪声频谱、测量     

R＆SFSW新增实时分析选件

由于在灵敏度、动态范围以及相位噪声方面的出色性能，罗德与施瓦茨公司的R＆SFSW高端信号与频谱分析仪成为雷达和卫星通信系统、军用和民用无线通信系统的组件和系统的研发和生产验证阶段理想的测量仪表。通过添加最新的R＆SFSW-K160R选件可以使R＆SFSW升级为实时频谱分析仪，从而使单台仪表不仅可以作为一台具备出色射频性能的传统频谱分析仪，同时可以无间隙地分析实时信号，在实时模式下的分析带宽高达160MHz。     

用脉冲计数技术提高接收机的灵敏度

本方法可以检测到低于 HP8551B 频谱分析仪噪声基底35dB 的弱微波信号。外差接收机通常不能检测功率电平低于系统灵敏度的输入信号。使用带有电子计数器的外差接收机可以提取比基底噪声低得多的这类弱信号。     

厂商动态

正RS公司发布支持500 MHz分析带宽的信号与频谱分析仪1月15日,罗德与施瓦茨(RS)发布了新的硬件选件RS FSW-B500,该选件可以安装在FSW全系列产品上,FSW的工作频率范围可达67 GHz。这一产品为射频微波信号分析领域打开了全新的局面,主要针对卫星通信、雷达以及宽带移动通信WLAN、后4G(5G)等高端应用。RS公司近期再次拓宽了其高端信号与频谱分析仪FSW的分析带宽,在以前320 MHz的基础上,首次突破500 MHz大关。500 MHz分析带宽对于脉冲测试的优势尤其     

影响频谱分析仪频率分辨率的因素

频率分辨率是频谱分析仪的一项重要技术指标,在介绍频谱分析仪原理的基础上,对频谱分析仪的分辨率带宽、频率选择性、本振残余调频和本振相位噪声参数进行了解析,从而使读者掌握各参数与频谱分析仪频率分辨率之间的关系,在选购频谱仪和实际测量时合理地考虑以上参数。     

A Method for Measuring Pulsed Amplifier Noise Using a Spectrum Analyzer

Measuring the noise generated by a pulsed RF amplifier is not a simple task [1]. One method of making this measurement converts the RF pulse to video with a phase detector and uses a spectrum analyzer to measure the noise between the lines of the pulse spectrum. The measurement includes the combined effects of timing jitter, power-supply modulation, and amplifier noise. An alternate method, described in this note, requires less test equipment by using an RF spectrum analyzer to measure the noise at a point outside the pulse spectrum. This measurement responds only to amplifier noise and is valid if the noise density is the same both inside and outside the pulse spectrum. Since this situation tends to be true of broad-band amplifiers such as TWT's and CFA's, the second method is preferable because of its relative simplicity. This note describes the procedure for measuring pulsed amplifier noise using an RF spectrum analyzer. The test setup and measurement procedure are described, as well as the conversion of the measured spectral-density ratio to an equivalent CW signal-to-noise ratio.     

RF instrumentation based on superconducting quantum interference

The application of the superconducting quantum interference device (SQUID) to RF measurements is reviewed. The SQUID can be adapted as a broadband standard of RF current, power and attenuation and may be used as the sensor for an extremely good regulator of RF current. Bandwidths of dc to 100 MHz and dc to 1 GHz have been demonstrated with a power sensitivity of ∼-100 dBm (100-MHz bandwidth, 0.1-dB resolution). In the measurement of attenuation 0.002 dB uncertainty can be achieved with similar bandwidths.     

射频模拟前端对数字中频接收机动态范围影响的研究

射频模拟前端(RFAF)是实现大动态宽带数字中频接收机(DIFR)的技术瓶颈之一,其在很大程度上制约着DIFR的带宽、动态范围等关键性能指标.本文研究实现宽带大动态DIFR的约束条件.基于ADC的性能指标,分析了RFAF的噪声系数、带宽以及中频欠采样的"处理增益"与DIFR灵敏度之间的关系,以及RFAF的增益和噪声系数与DIFR的动态范围之间的关系.推导并仿真了RFAF的增益和ADC的信噪比与DIFR的瞬时动态范围,以及数字自动增益控制(DAGC)的步长和调节范围与DIFR的扩展动态范围之间的关系.讨论了RFAF的最优化设计问题,给出了设计实例.     

Quantitative Comparison of Solid-State Microwave Detectors

A method for quantitative comparison of solid-state microwave square-law detectors is presented. The threshold response of the square-law detectors are compared for unit video bandwidth using the concept of noise equivalent power (NEP). NEP is the microwave input power required for unity signal-to-noise ratio in a 1 Hz bandwidth at the output of the detector. Contours of constant NEP in the microwave (RF) and video frequency plane clearly describe the dependence of threshold sensitivity on both video and radio frequencies, and thereby provide comparison of the threshold sensitivities of devices over the entire video and RF frequency spectrum. A criterion for the upper RF power lid of square-law operation for detectors is also presented. Dynamic range for a device can be found using this criterion and the threshold sensitivity of the device. Six solid-state detection devices are described briefly, then compared on the basis of the foregoing concepts. Four of these devices are familiar: the point-contact and planar Schottky-barrier ("hot carrier") diodes, and the tunnel and back diodes. Two relatively new devices are also discussed: the so-called "hot carrier" thermoelectric detector, and the space-charge-limited (SCL) dielectric diode.     

The Measurement of Noise in Microwave Transmitters

A tutorial review of the basis for transmitter noise measurements shows that noise is best described and measured as AM and FM noise. The determination of RF spectrum is done by calculation after the AM and FM noise are known. The contribution of AM noise to RF spectrum shape is determined by the power spectral density shape of the AM noise. The contribution of FM noise to RF spectrum is to make the shape that of an RLC circuit resonant response rather than a delta function with a sideband structure. The measurement of AM noise is done with a direct detector diode. The measurement of FM noise for frequencies above 5 GHz is done with a discriminator based on a one-port cavity resonator. The measurement of FM noise below 5 GHz is done with an improved transmission line discriminator which is described in detail. Measurement of low-power low-noise signal sources is made posbible with an injection-locked oscillator for a preamplifier to the discriminator. The most widely used baseband analyzer is the constant bandwidth superhetdrodyne wave or spectrum analyzer. Most differences in measurement results are resolved by understanding the baseband analyzers. At least the baseband spectrum analysis of transmitter noise measurements can be automated with worthwhile savings in time and improvement of documentation.     

毫米波雷达前端芯片关键技术探讨

毫米波雷达的距离分辨率和最大可工作距离通常受雷达射频信号带宽和发射功率的限制,具有宽工作带宽、高输出功率、高灵敏度、高精度相位控制的毫米波雷达芯片是实现高性能毫米波雷达系统的关键。毫米波雷达芯片的设计难点主要集中在阻抗匹配、噪声降低、功率提升、相位控制等方面。因此,该文针对毫米波雷达前端芯片设计难点的关键解决技术进行探讨和综述。     

A compact digital beamforming SMILE array for mobile communications

A compact spatial multiplexing of local elements (SMILE) scheme smart antenna array with adaptive beamforming is presented. Low-noise amplifiers are implemented as switching elements to maintain a low system noise figure and allow fast switching. The switching scheme effectively reduces N RF channels to one, reducing the amount of costly RF hardware by a factor of N. The sampling rate must be higher than the signal bandwidth based on the Nyquist criterion to ensure proper restoration of the original signal. Measured data for destination of arrival estimation, beamforming, and digital data recovery demonstrate the capability and benefits of digital beamforming with this architecture.