Dirty RF: A New Paradigm

The implementation challenge for new low-cost low-power wireless modem transceivers has continuously been growing with increased modem performance, bandwidth, and carrier frequency. Up to now we have been designing transceivers in a way that we are able to keep the analog (RF) problem domain widely separated from the digital signal processing design. However, with today’s deep sub-micron technology, analog impairments – “dirt effects” – are reaching a new problem level which requires a paradigm shift in the design of transceivers. Examples of these impairments are phase noise, non-linearities, I/Q imbalance, ADC impairments, etc. In the world of “Dirty RF” we assume to design digital signal processing such that we can cope with a new level of impairments, allowing lee-way in the requirements set on future RF sub-systems. This paper gives an overview of the topic and presents analytical evaluations of the performance losses due to RF impairments as well as algorithms that allow to live with imperfect RF by compensating the resulting error effects using digital baseband processing.     

基于残差神经网络的无人机射频信号识别

针对民用小型无人机对低空领域安全造成威胁及无人机视觉上识别难的问题,提出了一种无人机射频信号识别的方法,使用深度学习技术学习无人机与控制器之间的射频信号特征来识别无人机。首先将射频信号数据集中的无人机信号进行预处理操作,接着使用残差神经网络进行模型训练,最后使用训练好的网络模型对无人机信号进行识别验证。实验结果表明,该方法识别无人机是否存在的准确率达到99.8%,识别无人机型号的准确率达到91.1%,识别无人机运行模式的准确率达到70.3%,且该方法具备较强的鲁棒性和环境抗干扰能力,性能明显优于基准方法。     

基于自适应射频预失真的多载波功率放大器线性化技术

用高功率放大器放大线性调制信号 (包络波动变化 ) ,必然会产生失真和互调成分。而基于扩频技术的第三代无线通信系统中的功率放大器必须要有很好的线性性能。本文提出一种线性化射频多载波高功率放大器的自适应射频预失真器。     

基于射频识别物联网电磁场原理的研究

为了了解物联网应用拓展,探索RFID(射频识别技术)技术,文章从理论上对射频识别技术电磁场原理进行了探讨,从天线的电流模型出发,通过理论推导得出电磁量的计算公式,该公式对物联网具体的技术应用有一定的理论指导作用,对射频信号自动识别目标对象并获取相关数据,起到理论支撑作用。     

Analog and radio-frequency performance analysis of silicon-nanotube MOSFETs

This work presents a comparative study of the influence of various parameters on the analog and RF properties of silicon-nanotube MOSFETs and nanowire-based gate-all-around (GAA) MOSFETs. The important analog and RF performance parameters of SiNT FETs and GAA MOSFETs, namely drain current (I_d), transconductance to drain current ratio (g_m/I_d), I_on/I_off, the cut-off frequency (f_T) and the maximum frequency of oscillation (f_MAX) are evaluated with the help of Y- and H-parameters which are obtained from a 3-D device simulator, ATLAS^TM. It is found that the silicon-nanotube MOSFETs have far more superior analog and RF characteristics (g_m/I_d, f_T and f_MAX) compared to the nanowire-based gate-all-around GAA MOSFETs. The silicon-nanotube MOSFET shows an improvement of~2.5 and 3 times in the case of f_T and f_MAX values respectively compared with the nanowire-based gate-all-around (GAA) MOSFET.     

飞行器射频隐身技术及发展思路

射频隐身是武器平台对抗无源探测设备的重要技术手段,与雷达、红外隐身一起构成作战平台的隐身能力。飞行器射频隐身性能是其作战能力和生存能力达成的重要因素。在对飞行器典型有源传感器的使用和面临的威胁分析基础上,分析了飞行器射频隐身主要技术手段,概括了飞行器射频隐身主要技术特点,提出了飞行器射频隐身技术的发展思路。     

基于注入锁相的磁控管微波源系统稳定性研究与测试

基于5.8 GHz磁控管,研制测试了输出功率、频率稳定以及相位可控的大功率微波源系统.磁控管是整个系统的核心器件,由于其具有较高的DC?RF转换效率和功率质量比,选择磁控管作为系统的微波发生器.然而磁控管的输出频率不稳定、相位不可控,因此研究了以注入锁相和DDS+PLL频率合成为关键技术的相位控制系统,以实现对磁控管微波源系统输出信号频率和相位的控制,并测试了微波源系统输出功率、频率的稳定性以及相位控制系统的相位精度.测试显示微波源具有670 W的稳定输出功率,且频率稳定度≤10kHz,相位精度≤±2°.     

宽带RF信号光传输设备技术分析与实现

介绍了宽带RF信号直接光强度调制光发射机与光接收机的原理，分析了光传输系统中的载噪比、动态范围等重要指标。     

Beam dynamics and RF design of trapezoidal IH-RFQ with low energy spread

Beam dynamics and RF design have been performed of a new type trapezoidal IH-RFQ operating at 104 MHz for acceleration of 14C+ in the framework of RFQ based 14C AMS facility at Peking University. Low energy spread RFQ beam dynamics design was approached by the method of internal discrete bunching. 14C+ will be accelerated from 40 keV to 500 keV with the length of about 1.1 m. The designed transmission efficiency is better than 95% and the energy spread is as low as 0.6%. Combining the beam dynamics design, a trapezoidal IH-RFQ structure was proposed, which can be cooled more easily and has better mechanical performance than traditional RFQ. Electromagnetic field distribution was simulated by using CST Microwave Studio (MWS). The specific shunt impedance and the quality factor were optimized primarily.