Ka波段微带下变频器

下变频器简称高频头,是卫星电视接收系统的一个重要组成部分,它可对卫星下行信号进行放大和变频.与传统的C波段和Ku波段下变频器相比,Ka波段下变频器具有许多优点,正逐步在通信领域中得到应用.文中介绍了一种用于卫星直播系统的Ka波段微带下变频器,首先说明了其电路的工作原理和结构,然后研究了内部各模块的设计方法和用微波器件构造具体电路的实现过程.调试实验和实际接收表明该Ka波段下变频器具有良好的性能和较大的实用价值.     

Ka频段下变频模块设计

介绍了Ka频段下变频模块的设计。该模块的功能是将接收到的19.2~21.2GHz射频信号下变频到2.2~4.2GHz的中频信号。实际制作的下变频模块变频增益为20dB±1 dB,噪声系数小于6dB,镜频抑制大于100dB。该模块在Ka频段卫星通信系统中有着广阔的应用前景。试验结果证明,微波CAD工具的应用不仅降低了产品的研制成本,而且缩短了产品从电路设计到批量生产的时间。     

Ka频段卫星通信系统降雨衰减分析

Ka频段卫星通信因其具有可提供的带宽大(3.5GHz)、通信容量大、波束窄、终端尺寸小,轨道平面内可容纳的卫星多和抗干扰能力强等优势成为未来卫星通信的必然趋势。Ka频段卫星通信面临的一个巨大挑战在于它受气象因素的影响大,这一度使研究人员认为Ka频段卫星通信是不可能实现的。降雨、闪烁、大气吸收等因素都会导致Ka频段地空链路信道质量的恶化。根据Ka频段卫星通信的特点,分析了降雨衰减的特性,提出了几种抗雨衰的办法。     

Ka波段3dB定向耦合器的设计与仿真

定向耦合器广泛地用在现代微波系统中,文中介绍了两种应用在平衡式放大器中的3dB定向耦合器。首先对微带分支线耦合器与波导耦合器进行了理论分析,然后利用电磁仿真软件HFSS,对两种耦合器进行了建模仿真。仿真结果验证了这两种定向耦合器的可实现性,最后比较了两种耦合器的性能,并且总结了各自的特点。     

基于Ka频段的自适应MIMO调制算法

这里研究了一种应用于Ka频段卫星通信信道的自适应多输入多输出(MIMO,multiple-Input multiple-Out-put)调制算法,不同于一般Ka频段卫星通信的信道衰减补偿算法,该算法主要是能根据不同天气条件,利用MIMO系统的接收信噪比自适应的转换调制方式,以维持一定的目标比特率为目标,从而获取较高的系统吞吐量。仿真结果表明,该算法能有效应对Ka频段固定卫星通信信道下的严重信道衰落,兼顾系统性能和频谱效率,得到较高的吞吐量。     

Ka波段20W连续波宽带固态功放设计

采用空间功率合成与电路功率合成相结合的功率合成方式,设计了一款工作于Ka波段的连续波宽带20W功率放大器。采用分支波导电桥组合双探针波导-微带转换结构作为基本功率分配/合成单元,然后通过低损耗的4路波导T型结外合成,借助HFSS软件进行仿真优化,依托精密的机械加工技术,进而实现高效率的16路功率合成。测试结果显示：在Ka波段f0-5GHz到f0＋5GHz的频带范围内,该功率合成放大器带内最大饱和输出功率为29.5W（44.7dBm）,最大合成效率达92%。     

System concept for a digital repeater intended for a future generation of german telecommunication satellites

The derivation of a system concept for the digital multi-service repeater starts from evaluating the mission profile and the antenna concept elaborated so far. Furthermore, the repeater concept is shaped by Ka-band propagation conditions, the kind of integration of a down-link TV-distribution service into the prevailing multi-beam communications mode and readily available digital technologies. It is intended to embark on a completely regenerative approach using a unified switching concept for all services accompanied by a large amount of rearrangement functions in the foreground. An attempt is made to define those network control functions and procedures to be located on-board exploiting the fact that the repeater already acts as a central switching node. The discussion of on-board digital technologies concentrates upon a multicarrier demodulator concept and a candidate solution for the baseband switch. One general boundary condition is pronounced due to uncertainties about the actual traffic scenario in the future: all repeater resources must be accessible for the most important of the services considered, i.e. the provision of satellite business services.     

ACTS MOBILE TERMINALS

The development of the advanced communications technology satellite (ACTS) mobile terminal (AMT) and its follow-on, the broadband aeronautical terminal (BAT), have provided an excellent testbed for the evaluation of K- and Ka-band mobile satellite communications systems. Such systems have proved viable for many different commercial and government applications. Combining emerging satellite communications technologies such as ACTS' highly focused spotbeams with the smaller, higher-gain K- and Ka-band antenna technology, results in system designs that can support significantly higher throughput capacity than today's current commercial systems. An overview of both of these terminals is presented in this paper.     

Ka波段250W连续波行波管的研制

本文介绍了一种Ka波段连续波250W螺旋线行波管研制的主要技术方案。介绍了这种行波管的研究现状和研制成果。     

Ka波段500W脉冲空间行波管研制

针对空间探测领域的应用需求,本文采用大功率返波振荡抑制技术以及过渡波导输能技术,设计出了一种Ka波段580 W脉冲空间行波管。经过实际的样管测试验证,功率≥580 W,饱和增益≥47 dB,实现了Ka波段500 W脉冲空间行波管主要技术参数。