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排序方式: 共有107条查询结果,搜索用时 31 毫秒
81.
扇面波导连续长槽宽带天线 总被引:1,自引:0,他引:1
介绍扇面波导宽曲面上连续长槽天线,终端接匹配负载。导出了辐射槽的衰减系数和长槽任意点偏离波导宽面中心线的距离公式,并用于设计X波段长的连续曲线槽天线,具有满意的性能,如全频带指标等。 相似文献
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遗传算法在对数周期振子天线设计中的应用 总被引:1,自引:0,他引:1
首先简要介绍了对数周期振子天线(LPDA)理论的发展历史和本文采用的基本设计方法,其次在较详细地论述了遗传算法(基因算法)优化的步骤基础上,讨论了它在计算机优化设计LPDA中的应用.该算法的应用大大地简化了LPDA的设计过程,也显示了遗传算法在解决类似问题中的独到之处.最后给出了频率在0.1~1GHz的设计实例,获得了很好的结果.同时,本文就该算法在实际应用中优化变量和目标函数的选取方法进行了讨论;另外,还通过对该设计实例计算结果的分析,说明了在实际应用中,LPDA集总线终端接匹配负载和短路线时的天线性能差异,并给出了该现象的物理解释. 相似文献
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讨论了弹道导弹防御(BMD)系统的构成和作战过程。着重分析了BMD系统中的天基信息链,包括天基信息获取和天基信息传输,最后指出了天基信息链在未来信息化战争中必然起着重要的作用。 相似文献
86.
随着遥感、雷达、通信技术的快速发展,卫星有效载荷速率爆发式增长,星载固态存储器需要存储的数据量越来越大,存储速率越来越高,存储读写次数越来越多。作为当前星载固存的主流产品,基于FPGA和Nand flash的星载固态存储器所需的Nand flash数量越来越多,单片容量越来越大。受限于Nand flash的工艺特性,基于FPGA和Nand flash的固态存储器在其生命周期内会产生更多的坏块,从而影响记录载荷数据的正确性。针对星载固态存储器使用过程中产生再生坏块问题,提出了一种基于实时坏块检测、标注和坏块数据自主搬移、坏块自主回收的固态存储器坏块管理方案,有效地消除了再生坏块对载荷数据正确性的影响,降低了再生超级坏块数据的错误扩散和重复错误概率。方案已经过测试验证并已具有多个型号飞行经历,是一种简单、高效、可靠的星载固态存储器坏块管理方法。 相似文献
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Tethers are being proposed for a growing number of space applications. However, they may be particularly vulnerable to orbital debris and meteoroid impacts. In order to provide useful reference data for tether systems design, detailed analytical and numerical computations were carried out to assess the average impact rate of artificial debris and meteoroids. The specific geometric properties of tethers as debris targets, when compared to typical satellites, are discussed, and the results obtained are presented in tabular form, as a function of debris size and tether diameter.The computations were carried out for six circular orbits, spanning three altitudes (600, 800 and 1000km) and two inclinations (30° and 50°). Tether diameters in between 1mm and 2cm and debris larger than 0.1mm were considered in the analysis. The collision risk of tethers with spacecraft and upper stages in orbit was estimated as well.In the debris interval and orbital regimes considered, artificial debris represent the dominant contributor to the impact rate. At 600km and in the 0.1–10mm size range, the meteoroid and orbital debris impact rates are still comparable; however, at higher altitudes and in the 1–10cm size range, meteoroids contribute 20–30 times less to the collision probability.The results obtained confirm that for single-strand tethers in low Earth orbit the probability to be severed by orbital debris and meteoroid impacts is quite significant, making necessary the adoption of innovative designs for long duration missions. 相似文献
89.
Based on the concept of approximating antenna surfaces using flat facets or triangulated cable networks, a geometric scheme to subdivide a parabolic surface is discussed. According to the proposed scheme, the paraboloid is divided at the aperture circle into six equal segments first, which form a regular hexagon. Then the regular hexagon is subdivided into equal regular triangles to form subelements. Finally, the points of intersection of these triangles are projected or mapped on the paraboloid surface using a suitable origin of coordinates to obtain the final nodal coordinates of the members along the revolution axis direction. An expression for the relation between the systematic deviation of the actual surface from the desired surface and the side length of the regular triangles on the antenna's aperture surface is developed, which can be used to determine the side length of the regular triangles, and in turn to determine the size of the reflector surface facets necessary to meet antenna surface accuracy requirements. Application on a 0.6-m offset reflector is described and the simulation results demonstrate the effectiveness of the proposed technique in design of paraboloidal reflectors with flat facets. 相似文献
90.