共查询到20条相似文献,搜索用时 46 毫秒
1.
为适应卫星平台的需要,达到卫星天线能够实现角度扫描(正负5度)和机械扫描结构尽可能简单的要求,本文设计了一种三反射镜配置结构的角度扫描天线。首先利用几何光学法设计了赋形面,然后确定了在不同的扫描角度时,平面镜移动到的位置点。最后,利用高斯衍射波束分析方法(Diffraction Guassian Beam Analysis)进行了电性能的仿真验证。结果显示,在所需角度的扫描范围内,其具有较高的主面孔径利用效率和扫描机械结构简单的特点。在兼顾角度扫描和机械扫描结构简单的条件下,天线达到了所需的性能要求。 相似文献
2.
Direct Broadcast Satellites covering large countries such as Canada, require more than one spacecraft, located at different orbital positions, as well as the use of multiple shaped beams. This would minimize eclipse requirements over several time zones, provide increased capacity by frequency reuse and permit the use of cost effective ground receivers.Two such satellites are envisaged, one covering Eastern Canada, the other Western Canada, using two different sets of three highly shaped beams. This paper is the result of a feasibility study of a satellite antenna designed such that while at either orbital location it can be reconfigured in orbit, by ground command and hence can save the cost of one additional spare spacecraft.An offset parabolic reflector is proposed for the 12 GHz downlink, with a switched “dual feed” structure, consisting of two separate but contiguous sets of pyramidal horns and their associated beam forming networks (BFN). Only one BFN set is used at any one orbital location. Detailed radiation patterns demonstrate good beamshaping capabilities, with coverage efficiencies of the order of 94%. Other considerations such as the effect of orbital locations, gain equalization and TWTA standardization are discussed.It is concluded that a satellite, reconfigurable in orbit with a “dual feed” antenna, is feasible and cost effective, for a DBS spare as well as for the main spacecraft. 相似文献
3.
用于遥感卫星数传的新型波导阵列组合天线 总被引:2,自引:0,他引:2
从新的设计理念出发,提出一种新型的波导十字阵列组合辐射天线替代了赋形反射面天线,用于低轨遥感卫星的数传系统。文中论述了该天线的设计思路、设计过程,并列出了天线的主要性能。最后还简述了该天线在国内卫星上的应用及我国未来低轨遥感卫星数传天线的发展趋势。该天线已在我国多个卫星上成功应用。这种波导阵列组合天线结构紧凑、尺寸小,具有与国外通用的赋形反射面天线基本类似的性能,可达到星载数传天线的预定要求,而且为星载遥感器及其他载荷留出了更大的对地安装空间。 相似文献
4.
针对失效航天器大型天线进行再利用过程中的多细胞卫星(Satlet)布局问题,推导基于Lagrange方程的多Satlet天线动力学方程。通过分析天线振动对Satlet布局位置的影响和Satlet对天线系统的扰振,提出Satlet布局规划过程中的约束条件。在此基础上,采用遗传算法给出Satlet在天线系统中的最优布局,并采用协方差矩阵自适应进化策略(CMAES)对结果进行校验,以保证Satlet最优位置的准确性。仿真结果表明,失效航天器系统采用由上述优化算法给出的最优位置对Satlet进行布局,可以使得失效航天器的大型天线完成再利用过程中的姿态控制任务。 相似文献
5.
文章介绍了一种基本抛物面轴向6i指向-20°、-10°、0°、+10°和+20°的五焦点抛物反射面天线的设计,波束指向分别为-17.2°、-8.67°、0°、8.67°、17.2°。通过优化基本反射面的加权系数进行反射面的赋形,使每个波束的增益趋于均匀。对于标准偏置偏焦抛物面天线,波束指向±17.2°、±8.67°和0°时的增益分别为34.87dBi、38.67dBi和40.15dBi,边缘波束与中心波束的增益差值分别为5.28dBi和1.48dBi。用文中提出的方法得出对应波束的增益分别为36.10dBi、38.48dBi和39.14dBi,边缘波束与中心波束的增益差为3.03dBi和0.66dBi,与标准抛物面相比减小了2.24dBi和0.82dBi。 相似文献
6.
Recent studies have shown the feasibility of an Earth pole-sitter mission using low-thrust propulsion. This mission concept involves a spacecraft following the Earth's polar axis to have a continuous, hemispherical view of one of the Earth's poles. Such a view will enhance future Earth observation and telecommunications for high latitude and polar regions. To assess the accessibility of the pole-sitter orbit, this paper investigates optimum Earth pole-sitter transfers employing low-thrust propulsion. A launch from low Earth orbit (LEO) by a Soyuz Fregat upper stage is assumed after which solar electric propulsion is used to transfer the spacecraft to the pole-sitter orbit. The objective is to minimize the mass in LEO for a given spacecraft mass to be inserted into the pole-sitter orbit. The results are compared with a ballistic transfer that exploits manifold-like trajectories that wind onto the pole-sitter orbit. It is shown that, with respect to the ballistic case, low-thrust propulsion can achieve significant mass savings in excess of 200 kg for a pole-sitter spacecraft of 1000 kg upon insertion. To finally obtain a full low-thrust transfer from LEO up to the pole-sitter orbit, the Fregat launch is replaced by a low-thrust, minimum time spiral, which provides further mass savings, but at the cost of an increased time of flight. 相似文献
7.
Dipak K. Srinivasan David Artis Ben Baker Robert Stilwell Robert Wallis 《Acta Astronautica》2009,65(11-12):1639-1649
The NASA Radiation Belt Storm Probes (RBSP) mission, currently in Phase B, is a two-spacecraft, Earth-orbiting mission, which will launch in 2012. The spacecraft's S-band radio frequency (RF) telecommunications subsystem has three primary functions: provide spacecraft command capability, provide spacecraft telemetry and science data return, and provide accurate Doppler data for navigation. The primary communications link to the ground is via the Johns Hopkins University Applied Physics Laboratory's (JHU/APL) 18 m dish, with secondary links to the NASA 13 m Ground Network and the Tracking and Data Relay Spacecraft System (TDRSS) in single-access mode. The on-board RF subsystem features the APL-built coherent transceiver and in-house builds of a solid-state power amplifier and conical bifilar helix broad-beam antennas. The coherent transceiver provides coherency digitally, and controls the downlink data rate and encoding within its field-programmable gate array (FPGA). The transceiver also provides a critical command decoder (CCD) function, which is used to protect against box-level upsets in the C&DH subsystem. Because RBSP is a spin-stabilized mission, the antennas must be symmetric about the spin axis. Two broad-beam antennas point along both ends of the spin axis, providing communication coverage from boresight to 70°. An RF splitter excites both antennas; therefore, the mission is designed such that no communications are required close to 90° from the spin axis due to the interferometer effect from the two antennas. To maximize the total downlink volume from the spacecraft, the CCSDS File Delivery Protocol (CFDP) has been baselined for the RBSP mission. During real-time ground contacts with the APL ground station, downlinked files are checked for errors. Handshaking between flight and ground CFDP software results in requests to retransmit only the file fragments lost due to dropouts. This allows minimization of RF link margins, thereby maximizing data rate and thus data volume. 相似文献
8.
飞行事件系统责任保证链管理是航天器首飞试验质量管理的重要组成部分,是保证发射试验成功的重要管理手段。文章介绍了航天器首飞飞行事件系统责任保证链管理要点,并以某卫星天线展开事件为例介绍了飞行事件系统责任保证链管理实践。 相似文献
9.
面向大型反射面天线结构的机电综合设计与分析系统 总被引:2,自引:2,他引:0
针对天线机电分离设计的现状,研究了天线机电综合集成技术和天线组合结构理论, 并采用精确PO法分析天线远区辐射电场,建立了面天线参数化设计的层次结构,解决了由背 架、反射面和中心体等组成的组合结构网格自动划分难题,研制了天线结构分析与电磁计算 综合集成系统。实现了天线虚拟样机的参数化设计、机电性能分析与判断,可获得天线位移 云图、应力云图与电场方向图等准确的重要指标信息。该系统可用来指导天线结构设计人员 的工作,改进天线设计手段和方法,提升设计分析质量,达到缩短设计周期、降低设计成本 的目的。 相似文献
10.
关于双反射面天线的两个优化问题 总被引:1,自引:0,他引:1
在航天器上和地面站中,广泛采用着双反射面天线。本文探讨了双面天线的两个优化问题。当主面为现存的抛物面时,使副面优化赋形,从而比之经典双面(抛物面——双曲面)的增益提高(0.48~0.40)~(dB)(对应于D/λ=20~100)。寻求偏置柱形双反射面系统的最佳设计,使其在馈源方向图变化时,口径场分布最接近同相等幅。 相似文献
11.
12.
星载赋形反射面数传天线优化设计 总被引:1,自引:0,他引:1
为了使星载赋形反射面数传天线的波束形状满足设计要求,应用Minimax算法对其进行了优化设计。首先基于几何光学原理得到反射面中截线的初始形状,然后采用Newton插值函数对中截线进行拟合并把插值函数的系数作为优化变量,最终利用Minimax算法对优化变量进行调整来使获得理想的赋形波束。通过对一个X波段赋形反射面天线优化结果的分析及与基于几何光学原理综合算法所得结果的对比,表明此方法的有效性和优越性。数值仿真结果表明:该方法能够保证覆盖角域内任意一点的增益均高于设计指标要求。 相似文献
13.
In-orbit deployment characteristics of large deployable antenna reflector onboard Engineering Test Satellite VIII 总被引:6,自引:0,他引:6
This paper describes design, ground testing, an in-orbit experiment, and a novel in-orbit operation for large deployable antenna reflectors (LDRs). Two LDRs (TX-LDR for transmitting and RX-LDR for receiving) are installed on Engineering Test Satellite VIII (ETS-VIII). The reflector design features that the antenna reflector whose aperture is 13 m in diameter (the mechanical dimension is ) consists of 14 basic modules, and each basic module consists of a gold-plated molybdenum mesh, a system of cables, and a deployable frame structures. Several ground tests had been performed using a modular nature to advantage. Prior to the launch of ETS-VIII, we performed an in-orbit deployment experiment using LDREX-2 which consists of seven half-scale modules of LDR, to confirm evaluation accuracy. The LDREX-2 was launched by ARIANE 5 launch vehicle as a piggy-back payload. Deployment characteristics were measured to evaluate the accuracy of analytical prediction obtained by ground deployment testing. ETS-VIII was launched by H-IIA launch vehicle on 18 December 2006. After the successful injection into Geo Synchronous Orbit, the RX-LDR and the TX-LDR were successfully deployed on December 25th and 26th, respectively. We confirmed adequacy of the proposed design and ground verification methodology. 相似文献
14.
15.
Yuri V. Trifonov 《Acta Astronautica》1996,39(9-12):1021-1024
The preliminary estimations show that the contemporary level of electronic and information engineering makes it possible to create a small s/c of 150–200 kg mass capable to solve both the problems of Earth remote sensing and many other applied and scientific problems orbiting the planets at 500–1000 km. In accordance with the fundamental criterion for choosing parameters of small multipurpose spacecraft the small UNISAT s/c has been created on the basis of a unified space platform. The design provides for s/c energetic, thermal and space-saving parameters satisfying the conditions for accommodation of various-purpose payload and a possibility of using relatively inexpensive and light launchers like “Start-1” mobile launch complexes. Space platform mass is 100–120 kg; permissible payloads (PL) mass is 40–80 kg; maximal average power consumption of the payload is up to 60 W; three-axes orientation accuracy up to 0.001 deg./s; s/c lifetime is not less than 3–5 years. 相似文献
16.
为满足星载高增益天线的应用需求,本文设计了一种带有相控阵馈源的伞状可展开反射面天线。首先介绍了反射面天线可展开机构的原理及设计,由碳纤维天线肋和金属编织网面组成反射面,在高精度可展开机构的动作下实现其收拢和展开,从而大幅减小其收藏包络尺寸。对于直径为1.14 m的可展开反射面天线设计了宽带相控阵馈源,采用金属Vivaldi天线作为相控阵单元,根据极化方式、焦径比和扫描范围选择排列成双极化矩形阵列,使可展开反射面天线在8~16 GHz内实现二维波束扫描,通过电磁仿真进行验证,仿真结果表明,宽带相控阵馈源能够有效地增加可展开反射面天线的视场,反射面天线在8 GHz、12 GHz和16 GHz时扫描到0°的增益分别是38.03 dB、40.65 dB和41.48 dB,扫描到+3°的增益分别是37.68 dB、40.68 dB和41.09 dB。 相似文献
17.
18.
R.L. Harvey 《Acta Astronautica》1980,7(10):1191-1211
Using a baseline design for a 30/20 GHz system, this paper addresses the critical technical issues of signal waveform design, projected spacecraft technology, satellite launch options and satellite cost. With DPCM (differential pulse-coded modulation) video signal encoding, 32 Mb/s user-to-user data rate per channel, 10% overhead, two orthogonal polarizations, and crosstalk loss limited to 1 dB, TFM (tamed frequency modulation—a type of QPSK) permits about 75 channels/GHz of frequency allocation, i.e. about twice the capacity possible with MSK or SFSK (types of QPSK). The BOM (beginning of mission) weight and power of a baseline 400-channel multi-beam satellite is about 1800 kg and 5000 W. Each 35 Mb/s channel can support 1–10 video channels depending on the signal processing at the ground terminals. These weight and power estimates assume hardened digital logic, composite material for a multibeam antenna structure, high-efficiency solar cells (45 W/kg), NiH2 batteries and 10W/20 GHz power amplifiers. If more speculative late-1980s solar cell technology is assumed, then the BOM weight decreases about 10–15%. Using the Space Transportation System being developed by NASA, geosynchronous deployment options are shown as a function of communications capacity. Based on a cost model for large communication satellites, the total space segment cost of two active satellites and one spare would be about $485M. This system would have a peak capacity of 14 Gb/s or 400-35 Mb/s simultaneous one-way channels. Demonstration and/or initial system (ground plus space) costs would be significantly less. It is concluded that the above baseline satellite appears to be technically feasible in the late-1980s. 相似文献
19.
为探究反射面天线形变对风云卫星毫米波和亚毫米波成像仪(MMSI)的亮温图像质量的影响,运用基于表面电流积分的物理光学方法计算天线辐射方向图,探究不同形式反射面天线形变下天线辐射特性的变化规律。结合MMSI的亮温图像的处理结果,评价图像质量的变化。实验结果表明:反射面天线的形变面积、形变位置和副反射面晃动发生变化时,天线的主瓣增益、副瓣电平和波束宽度等关键指标发生规律性变化,对MMSI的亮温图像质量产生不同形式的影响。当反射面天线的形变面积增大时,天线的主瓣增益减小,副瓣电平升高,进一步导致分辨率降低,噪声水平升高,亮温图像质量变差。 相似文献