宽带大功率限幅器小型化研究

采用微波混合集成电路设计方法,用并联二极管和检波二极管,在很小的腔体内制作了无源微波限幅器。其电参数为:频率范围2~18GHz;承受功率4W(连续波);限幅电平≤30mW(Pin为4W,连续波);插入损耗为2.5dB以下;驻波系数为2.0以下。外形尺寸为13.5mm×6mm×3mm;输入输出端为50?绝缘子。     

高功率光纤激光器发展概况

高功率光纤激光器以其优越的性能和超值的价格,在光通信、印刷、打标、材料加工、医疗等领域有着广阔的应用,将会很大程度上替代传统激光器,并开辟一些新的激光应用领域,扩大激光产业的规模.概述国内外高功率光纤激光器的发展历史与现状.展望了高功率光纤激光器的发展前景.     

A high-power wideband traveling-wave tube with stepwise changes in the diameter of the drift channel

Results of the design of a high-power wideband (in the band 8–18 GHz) traveling-wave tube (TWT) with stepwise changes in the diameter of the drift channel are presented. The TWT is stable against self-excitation by a backward wave at high values of the accelerating voltage. It is shown that the output section of the device can be increased by a factor of 1.5 and the operating current can be raised by a factor of 1.3. These increases are attained owing to the 1.27-GHz diversity of the π-type frequencies of sections with different values of the channel diameter and owing to growth of the starting current corresponding to self-excitation by the backward wave. Application of the TWT with the interaction space that has steps of the channel diameter improved the electron efficiency by a factor of 1.2 and increased the output power by a factor of 1.6.     

Ultra wideband antenna

Ultra wideband antennas are specifically designed to transmit and/or receive very short time durations of electromagnetic energy. It is well known that UWB antenna design remains the major factor in the progress of UWB technology. This article describes a study of conventional antennas and why they are not suitable for a UWB system.     

Radiation performance improvement of wideband microstrip antenna array using wideband AMC structure

In this paper, the radiation performance of an antenna array is improved by designing a new wideband artificial magnetic conductor (AMC). The proposed AMC surface operates at the frequency of 3 GHz with ±90^° reflection phase bandwidth of 22%. In order to identify the key design parameters of the AMC structure, a parametric study is performed. To improve the radiation performance of the antenna array, an AMC reflector is developed through utilizing an array of 2 × 8 periodic patches of AMC unit cells. By this technique, the front to back ratio of the designed antenna array is enhanced about 16.27 dB. It is concluded that tuning of the AMC dimensions for controlling the reflection coefficient at each port of antenna array during beam steering is necessary. Because of the using of the AMC surfaces as a reflector instead of conventional PEC surfaces, size reduction of the antenna array in the order of 20% is achieved. In this study, a circuit model for single element of the antenna array with considering AMC loading effect is introduced, which predicts the bandwidth behaviour of the proposed antenna. The final designed antenna array exhibits low level of cross polarization making it well‐suited for tracking radars and electronic warfare applications. The proposed antenna with the AMC reflector is fabricated and measured. The measured ?10 dB impedance bandwidth and peak gain of the proposed antenna is 20% (2.7‐3.25 GHz) and 13.4 dBi, respectively, which are compatible with the simulation results.     

高功率发光二极管的应用

发光二极管(LED)因其在光输出上获得了新突破而得到了更加广泛的应用。其应用范围将从牙齿的医疗养护到飞机座舱的照明，以及汽车的前照灯。     

Very wideband corrugated horns

An expression for the input impedance of a short-circuited, linearly-tapered transmission line is derived. The use of tapered slots in a corrugated horn is proposed as a means of broadening their bandwidth to greater than 3:1. Test results are presented for an experimental horn operating over the full 7.5?18 GHz range of DR14 waveguide.     

世界平板显示器市场新观察

几年前，某些业界著名人士曾预言，到２０世纪末所有 ＣＲＴ（阴极射线管）都将被无情淘汰，而代之以平板显示器，特别是液晶显示器。 这在当时是一种幻想，今天的事实更戳破了那种幻想。ＣＲＴ市场继续增长，并牢固地主宰着ＰＣ监视器和电视机市场，在未来几年内也没有被淘汰出局的迹象。 １９９４年，日本若干有名报刊在日本电子界名门大户提供信息的基础上，曾预测２０００年平板显示器市场将高达４００亿美元。它们同样认为，古老成熟的ＣＲＴ即将退出电视机和台式ＰＣ监视器市场，美梦未能成真。专做显示器市场调查研究的美国Ｓｔａｎ…     

Photonic wideband array antennas

Presents an introduction to the optical control of array antennas by using fiber optic links for remote control and a photonic time shift network for wide instantaneous bandwidth. An overview of the development of a wideband conformal array designed for airborne surveillance radars is given. The paper covers the system design and the performance of an L-band (850-1400 MHz) M-element array controlled by photonics. Packaging techniques of the photonic components and the array aperture are discussed. The wideband performance of the system is highlighted. A nano-second impulse response has been measured to demonstrate a 50% instantaneous bandwidth (550 MHz, 30 cm range resolution) for target ID and imaging. A built-in signal injection technique based on time-domain impulse measurement was used to calibrate the wideband components in the time-shift beamforming network     

Dual-polarised wideband microstrip antenna

A dual-polarised aperture-coupled microstrip antenna with a wide bandwidth, a high isolation, low cross-polarisation levels and low backward radiation levels is presented. The square patch is fed at two corners via H-shaped apertures. The measured return loss exhibits a bandwidth of over 24.4% and the isolation is better than 30 dB over the bandwidth. The cross-polarisation levels and the front-to-back ratio are better than -23 and 22 dB, respectively     

New wideband sigma-delta convertor

A new kind of sigma-delta modulator made with a double integrator and a bandpass stage is presented. It can reduce the oversampling ratio or increase the bandwidth for a constant sampling frequency compared with equivalent complexity modulators.<>     

全球2018年DRAM产业预估预测

本文介绍了2017年DRAM市场状况,并对2018年的DRAM市场进行了分析预测.2018年预计仅增长19.6%,无大规模增产计划下,供给将延续吃紧走势.     

中外石墨烯产业化发展管窥

石墨烯因其优异的热学、电学、力学等性能,在各领域备受青睐。本文对石墨烯在新能源电池、复合材料、功能涂料等领域呈现的良好商业化前景进行概述。同时,还分析对比了各国石墨烯产业的发展现状和政策支持。     

世界半导体市场展望

正半导体市场美国Microchip Technology曾于10月曾预测今年3季度公司营收下降的消息,并指出该公司以及Intel和TI的股票都下降了,意味着今年世界半导体业或将下行,一石掀起千层浪,True or False?引起了debate!未几日Intel宣布说3季度营收,达到147亿美元,创历史新高。同时,TI也发表了同期的业绩超过预期,涤荡了Microchip Technology几天前所散布的半導体業容或低迷的阴霾。事实上,据10月     

Overview of wideband packet protocols

Wideband packet networks operate at rates equal to, or higher than, 64 kb/s, but lower than the basic broadband rate of 150 Mb/s, on cables or satellite links. Wideband packet protocols are the transmission protocols for these networks. They define open interfaces that can be used for public and private ISDNs. The protocols are defined in CCITT Recommendations G.764 and G.765. This paper describes the objectives of the wideband protocols, and how the objectives were achieved.     

Compact wideband bandpass filter

Designing wideband bandpass filters (BPF) with parallel-coupled microstrip lines requires tight coupling resulting in close separation between the lines and difficulty of fabrication. Here, it is shown that the etched slots in the ground plane of the parallel coupled lines can significantly increase the coupling. This technique has been extended to realize ultra-wideband BPFs having 3-dB fractional bandwidth greater than 100% and low insertion loss in the passband.     

All-fibre wideband polarisation beam-combiner

An all-fibre polarisation beam-combiner with more than 200 nm spectral width for -15 dB extinction ratio is demonstrated. The design is based on a narrowband polarisation beam-combiner coupler in association with a WDM coupler in a Mach-Zehnder interferometer structure.     

全球掀起RFID热潮

在机场、港口、铁路货场、仓库、货柜码头、大型商场等物流中心的RFID(射频识别)标签和读写器无处不在,组成空中的物流跟踪和监管系统.全球正掀起一股RFID热潮,点燃信息技术应用的新亮点,RFID的核心技术是一块集成电路,每块芯片含有RFID数据,读出器可在远距离读取芯片存储的数据,无须在视线距离内作扫描或物理接触.     

Robust demodulation of wideband signals

Asymptotically robust algorithms for demodulation of phase-modulated signals in the presence of noise with an unknown distribution are obtained on the basis of the invariance and minimax principles. Stable quality indices of the algorithms are achieved in the case when the noise level and the shape of its distribution are a priori uncertain. An adaptive variant of the robust algorithm that can be adjusted to an actual noise distribution is presented.