5G 2.6 GHz与700 MHz频段基站天线建设策略

针对中国移动基站天馈"两多一快"特点及面临的天面租金贵、资源紧张挑战,提出统筹考虑制式频段、采用多频段多端口独立电调天线进行天面整合的天馈建设总体思路.确定以单小区2天面为主的天面目标,"有源、无源分割"、"TDD、FDD分割"的天馈整合原则.统筹考虑5G 2.6 GHz与700 MHz,结合后续5G建设节奏,确定4个...     

应用于动态核极化核磁共振系统的改进型传输线研究

基于几何光学理论和矢量衍射理论,设计了263 GHz DNP-NMR谱仪的改进反射镜系统,并进行了数值模拟.该系统包括两个波纹波导、一个抛物面镜和一个角度可调的相位校正镜.仿真结果表明,获得了聚焦良好的类高斯输出光束,其标量高斯模含量为99.90%,矢量高斯模含量为99.55%.只有通过调整相位校正镜的角度来匹配DNP-NMR样品,才能改变输出光束的方向.当输出光束方向在±15^o变化时,标量高斯模含量约为99.57%,矢量高斯模含量约为98.97%.     

94GHzTE5,3准光辐射器

基于耦合波理论和相位匹配技术,对准光辐射器的传统设计方法进行了改进,使其适用于低阶模式的设计.通过调节耦合时模式间的相位,在切口处实现了具有高斯场分布的理想模式组合.利用这一方法,优化设计了一个94 GHz,TE5,3回旋管准光辐射器.数值模拟结果表明,设计的辐射器在切口处形成了一个良好的束斑,边馈电平达到-30 dB,口径场高斯含量高于98%.     

Continuously Tunable 250 GHz Gyrotron with a Double Disk Window for DNP-NMR Spectroscopy

In this paper, we describe the design and experimental results from the rebuild of a 250 GHz gyrotron used for Dynamic Nuclear Polarization enhanced Nuclear Magnetic Resonance spectroscopy on a 380 MHz spectrometer. Tuning bandwidth of approximately 2 GHz is easily achieved at a fixed magnetic field of 9.24 T and a beam current of 95 mA producing an average output power of >10 W over the entire tuning band. This tube incorporates a double disk output sapphire window in order to maximize the transmission at 250.58 GHz. DNP Signal enhancement of >125 is achieved on a ¹³C-Urea sample using this gyrotron.     

Low-noise 460 GHz waveguide Schottky mixer radiometer for radioastronomy

We report measurements on a cryogenically cooled Schottky barrier diode mixer system at 460 GHz. The mixer and horn are electroformed in a single block, and the carcinotron local oscillator is coupled in through a polarisation diplexer. A double-sideband system noise temperature of 870 K was obtained at midband at 12 K ambient. The total RF/IF double-sideband conversion loss was 9.0 dB, measured at 295 K ambient.     

170 GHz兆瓦级回旋管横向磁场扫描线圈组设计

170 GHz兆瓦级回旋管是热核聚变等离子体加热用电子回旋谐振系统最重要的功率源。在获得兆瓦级连续波输出功率的同时,收集极功率密度过大成为限制整管平均功率和脉宽进一步提升的主要问题。因此,设计了具备周期性变化的横向磁场扫描线圈组。通过仿真分析收集极内的电子注分布可知,采用该线圈组可以有效降低功率密度,从而保证整管稳定工作。同时,对不同电流相位的线圈组的性能进行对比分析,优化后的横向磁场扫描线圈组可使收集极平均功率密度由4.7 kW/cm2下降到0.29 kW/cm2,将被应用到未来170 GHz兆瓦级回旋管的热测中。     

Numerical simulation of mode interaction in 170 GHz/1 MW gyrotrons for iter

The paper presents an advanced method for and results of calculating main parameters of CW 170 GHz/1 MW gyrotrons operating at the TE_28.7 and TE_31.8 modes for ITER. Parameters are optimized to achieve maximum efficiency of the gyrotron with an acceptable Ohmic load on the cavity. Numerical modeling of starting up a gyrotron with an optimized cavity and processes of mode interaction are discussed.     

一种700 MHz频段的高线性驱动放大器MMIC

采用GaAsPHEMT工艺,设计了一种700 MHz频段的高线性驱动放大器MMIC.该放大器内部集成了带通复合匹配网络结构的宽带输入匹配电路,通过两种幅频特性相反的匹配网络进行组合,有效地拓展了应用带宽,提高了线性度和增益平坦度.放大电路采用两级放大结构,保证增益指标,引入稳定性设计以保证放大器工作的稳定性.偏置电路采用带负反馈系统的有源镜像结构,提高了驱动能力,使电路更加稳定.该放大器集成输出检波器,采用二极管检波器结构实现功率检波,具有结构简单、占用芯片面积小的优点.该放大器典型频点700 MHz处的输出三阶交调点为42.6 dBm,1 dB压缩点输出功率为27.6 dBm.通过调整片外输出匹配电路可满足700 MHz及其他频段的应用需求.     

700 MHz时代下广电业务在山区的发展策略

由于700 MHz信号覆盖广、穿透力强,且实现成本较为低廉,因此在山区有着极高的应用价值,为山区广电业务的发展带来了新的契机.在分析我国700 MHz技术优势和发展现状的基础上,就如何利用700 MHz时代带来的机遇发展山区广电业务提出一些思路,以供参考.     

厦门市700 MHz频谱使用现状及干扰隐患

5G系统是我国实施“两个强国”战略的重要信息基础设施,更是发展新一代信息通信技术的高地。700 MHz作为最新规划的5G低频段频谱资源,将进一步提升5G通信技术的发展。重点介绍了厦门市700 MHz频谱的使用现状,存在的干扰隐患及解决建议。     

700 MHz NR共享频谱使用策略分析

本文针对700 MHz NR低频与大带宽的优势,基于建网初期5G网络利用率低,同时4G网络利用率高的情况,探讨NR与LTE在同一频谱上根据业务量需求进行时频资源的瞬时动态频谱共享与灵活的功率分配的方法,以及NR与LTE小区共享同一段频谱资源时对上下行物理信道资源进行合理协调调度来规避冲突并提升频谱使用效率的方案,保障N...     

B超对黄体酮治疗妊娠期输尿管结石的观察

该文介绍了声光器件的工作原理,研究了在相同输入功率下得到的声光衍射功率值;实验以700 MHz声光器件进行测试,得到实验数据.通过实验数据分析得到声光器件具有一定的噪声抑制能力(实验测试计算的噪声系数NF<1),为声光器件在信号处理中的性能设计提供了实验依据.     

Development of gyrotrons at Thomson-CSF†

In this paper, experimental results on a 35 GHz 250 kw gyrotron oscillator (TH 1501 A) are first summarized. The project of a 70 GHz oscillator operating on the second harmonic of the cyclotron resonance is then discussed, and first experimental results are described. Theoretical work on space charge effects in a single orbit cylindrical beam oscillator is also reported. Numerical results indicate typically a 15% decrease in logarithmic gain.     

关于700 MHz频段用于LTE网络的研究与探讨

700 MHz频段具有优质的传播特性,有利于IMT系统实现快速部署。通过分析国内频谱分配现状及全球运营商的LTE商用网络频段使用策略,指出国内现有LTE网络部署缺乏低频谱资源,不利于LTE网络实现低成本快速部署。700 MHz已成为国际应用LTE主流频段之一,而我国尚未明确700 MHz频谱的应用规划。随着广电行业地面电视模数转换进程的推进,建议政府相关部门主导,区域性推动700 MHz频段广电清频,并明确相关规划。     

5G NR部署在700 MHz上的综合性能分析

为有效进行700 MHz频段5G网络的规划和部署.本文通过链路预算,计算了700 MHz频段最大允许的路径损耗,再结合传播模型,给出了700 MHz频段的覆盖能力.在密集市区、一般市区、郊区和农村场景下,700 MHz频段的小区覆盖半径分别是447 m、623 m、877 m和2074 m.通过参数法给出了700 MH...     

5G 700 MHz频段干扰有线电视信号的处理方法

目前,中移通信技术有限公司已在大范围使用5G 700 MHz频段.700 MHz下行信号干扰广电有线的范围和点位也在不断增多,目前受影响的主要是县乡区域.该问题导致有线电视同频下的数字信号劣化,节目出现间歇性马赛克现象.为此,以实际故障处理过程为案例进行分析,从接入网和频点的优化入手,切实解决同频干扰问题.     

Development of 394.6 GHz CW Gyrotron (Gyrotron FU CW II) for DNP/Proton-NMR at 600 MHz

Gyrotron FU CW II with an 8 T liquid He free superconducting magnet, the second gyrotron of the THz Gyrotron FU CW Series, has been constructed and the operation test was successfully carried out. It will be used for enhancing the sensitivity of 600 MHz proton-NMR by use of Dynamic Nuclear Polarization (DNP). The designed operation mode of the gyrotron is TE_2,6 at the second harmonic. The corresponding frequency is 394.6 GHz. The real operation frequency is 394.3 GHz at TE₀₆ mode, because of fabrication error of the diameter of the cavity. The operation is in complete CW at the output power of around 30 W or higher at the TE₀₆ cavity mode. There are many other operation modes at the fundamental and the second harmonic. Typical output power of the fundamental and the second harmonic are higher than 100 W and 20 W, respectively. The highest frequency observed up to the present is 443.5 GHz at the second harmonic operation of TE_6,5 mode. The measured results are compared with the theoretical consideration.     

Development of multimegawatt gyrotrons for fusion plasma heating and current drive

High-frequency gyrotrons with high output power are mainly used for microwave heating and current drive in plasmas for thermonuclear fusion. The development of high-power gyrotrons in continuous wave (CW) operation has been in progress for several years in a joint collaboration between different European research centers and an industrial partner. The status of the development of the 140-GHz continuously operating gyrotrons with an output power of 1 MW for the stellarator Wendelstein 7-X will be described. An output power of 890 kW has been achieved with a pulse length of 3 min. limited by the available high-voltage power supply at an electron beam current of 40 A. At a reduced beam current of 27 A , an output power of 540 kW was measured with a pulse length of 939 s. For the next fusion plasma device international thermonuclear experimental reactor, gyrotrons with a higher output power of about 2 MW are desirable. In short-pulse experiments, the feasibility of fabrication of coaxial cavity gyrotrons with an output power up to 2 MW, CW, has been demonstrated, and the information necessary for a technical design has been obtained. An output power of 2.2 MW has been reached in stable operation (without mode competition). At the nominal output power of 1.5 MW an efficiency of 48% could be obtained with single-stage depressed collector. The development of frequency tunable gyrotrons operating in the range from 105 to 140 GHz for stabilization of current driven plasma instabilities in fusion plasma devices (neoclassical tearing modes) is another task in the development of gyrotrons at the Forschungszentrum Karlsruhe.