Ka频段大口径测控天线无人机校相方法设计与验证

面向Ka频段航天测控设备天线标校工程应用需求,分析了大口径测控天线相位校准方法原理,论证设计了轻量化、模块化的组合式测控应答机无人机装载模式,提出了基于无人机的S频段天线自跟踪叠加偏置进行Ka频段天线快速校相的方法,并进行了跟踪精度分析。计算了在不同地面测控天线口径下进行相位标校的链路余量,规划了无人机飞行航路和试验步骤,并进行了Ka频段天线快速校相、电轴一致性测试试验,每次相位标校得出的交叉耦合和灵敏度系数指标均满足天线对无人机信标的闭环自跟踪要求。结果表明,基于无人机平台的大口径测控天线相位校准方法能够为Ka频段测控设备标校提供一种新的手段,具有良好的工程应用前景。     

Cloud attenuation statistics from radiometric measurements over a tropical location Kolkata,India

The objective of this study is to investigate cloud attenuation at 30 GHz frequency using ground-based microwave radiometric observations at a tropical location, Kolkata. At higher frequencies and lower elevation angles, cloud attenuation is of major concern at a tropical location. The location experiences high value of liquid water path (LWP), which is responsible for cloud attenuation, during the Indian summer monsoon (ISM) and pre-monsoon season. Significant amount of cloud attenuation has been observed during monsoon season at 30 GHz. Two years observations of exceedance probability of cloud attenuation and worst month statistics are presented. The variation of cloud attenuation with frequencies for different elevation angles has also been investigated. The seasonal and diurnal patterns of cloud attenuation are examined. Cloud attenuation, inferred from radiometric measurements before rain commencement, has been compared to rain attenuation at Ku-band. Exceedance probabilities of cloud and rain attenuation have been compared.     

槽流的亚临界转捩与局地湍流

在中低雷诺数时,处于线性稳定的槽道流若受到强扰动可发生亚临界转捩变为湍流。近年人们对该类转捩机理的研究取得重要进展。对于平板泊肃叶流,亚临界转捩之初是稀疏湍流态,其特征结构是远间隔的包含小尺度涡和高低速条带的大尺度的湍流带,可倾斜伸长。该阶段的湍流占比有上限但并非雷诺数的单值函数。随着雷诺数的增加转捩进入平衡局地湍流态,即存在统计定常态,其湍流占比是雷诺数单值函数,可由定向逾渗模型描述。进一步增加雷诺数,湍流带的分裂愈发频繁,最终流场会布满湍流带,在更高的雷诺数时变为均匀湍流。论文概述了为比拟亚临界转捩过程所提出的动力学模型,以及为定量表征管流、平板库艾特流和平板泊肃叶流转捩过程的相似性所提出的局地稳定性参数,并在最后对槽道流亚临界转捩研究的发展做了简要展望。     

MWSF微波选频组件快速测试方法

针对MWSF微波选频组件故障率高，开发了一种可行的测试方法，解决了MWSF微波选频组件快速测试问题。     

一种窄带辐射温度计智能标定及检定系统

文章描述了由串行电可改写擦除存储器（ＥＰＲＯＭ）、ＲＳ－２３２通讯口和个人计算机（ＰＣ）组成的窄带辐射温度计标定检定系统。系统除了能够在标定过程中自动完成仪器的标定，给出听输出误差分布、提高仪器的速度以外，在检定时还可以通过修改检定参数很容易地修正仪器的各种源移量，使被检测仪器无需作入动或调整即可重新使用。     

基于空间隔离的低轨卫星系统频谱共享方法

随着业务需求的全球性增长,传统低频波段有限的频谱资源已不能满足低轨（LEO）卫星的业务承载要求,采用Ka频段的LEO星座系统设计成为了主流。然而,采用Ka频段的LEO星座系统不可避免地会对同频段已经存在的静止轨道（GEO）卫星系统产生干扰。首先,通过基于空间隔离的干扰规避方法,采用对LEO与GEO的频谱共用系统设置隔离角来进行上下行场景的干扰消除,使该LEO系统能满足国际电信联盟（ITU）对同频段内通信干扰的约束条件;然后,通过引入GEO带的概念,分析并研究了干扰规避区域的确定方法和其对LEO星座密度的影响。最后,通过仿真得出了干扰隔离角、GEO带与LEO星座密度的关系,得到了在采用隔离角的方式进行干扰避让时满足LEO星座系统业务不中断所需要的最小卫星数量,对LEO星座设计具有一定的指导意义。      

Fault-tolerance wide voltage conversion gain DC/DC converter for more electric aircraft

In this paper, a fault-tolerance wide voltage conversion gain DC/DC converter for More Electric Aircraft (MEA) is proposed. The proposed converter consists of a basic Cuk converter module and n expandable units. By adjusting the operation state of the expandable units, the voltage conversion gain of the proposed converter could be regulated, which makes it available for wide voltage conversion applications. Especially, since mutual redundancy can be realized between the basic Cuk converter module and the expandable units, the converter can continuously work when an unpredictable fault occurs to the fault-tolerant parts of the proposed converter, which reflects the fault tolerance of the converter and significantly improves the reliability of the system. Moreover, the advantages of small input current ripple, automatic current sharing and low voltage stress are also integrated in this converter. The working principle and features of the proposed converter are mainly introduced, and an experimental prototype with 800 W output power has been manufactured to verify the practicability and availability of the proposed converter.     

大功率高效率星载固态功率放大器研究

针对卫星系统对于微波大功率放大器的需求,研制了L频段200W高效率固态功率放大器,对其设计方法和关键技术进行了详细论述。应用低温共烧多层陶瓷技术,实现了射频电路的高集成和小型化;基于第三代半导体器件,应用波形赋形及线性补偿技术,提升了射频电路的功率和效率;采用移相全桥拓扑,研制了高效率、大功率二次电源。在1.45~1.55GHz的频带范围内,固放整机输出功率大于200W,效率高于60%,3阶交调优于18dBc,同时具备30dB增益可调,360°内步进5.6°的相位可调能力。试验结果表明,该固放为目前国内星载领域连续波功率和效率最高的单机。     

高动态环境中导弹捷联惯导系统圆锥误差

分析了高动态环境中导弹捷联惯导系统(SINS)圆锥误差形成的原因。研究了由陀螺频带不足、量化误差和安装误差，以及姿态更新率过低造成的圆锥误差。给出了计算公式，并在一定条件下计算了误差的大小。分析结果表明．不能正确感测运载体的角运动和姿态更新率过低是引起圆锥误差的主要因素。     

S波段超小型锁相信标机的设计与实现

介绍一种新研制的超小型信标机 ,该机采用锁相环技术 ,输出信号质量高。信标机安装在氢气球悬挂的金属铝球内 ,可综合检验同一场区内的引导雷达、脉冲雷达、遥测跟踪站等设备的动态跟踪性能 ,实现测控系统的动态联调和合练。