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论群速相速概念与电磁波传播模式 被引量:2
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作者 邵建军 《培训与研究(湖北教育学院学报)》 2005年第5期4-10,共7页
文章研究了电磁波传播的群速与相速概念,论证了信号传送与能量传递的必然联系。研究了波导模式理论与单模传播条件,电磁波在等离子体中传播时的信号传送速度,并讨论了传输线的色散问题。
关键词 群速与相速 波导模式 单模传播 等离子体 传输线色散
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短波信道频率相对时延的实测分析
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作者 邹显炳 李少谦 《电子科技大学学报》 EI CAS CSCD 北大核心 2003年第5期551-554,共4页
利用电离层斜向探测系统分别对三条短波路径进行了时延测试,在单模传播数据曲线拟合的基础上,计算了短波信道频率相对时延值,重点分析了电离层单模传播情况下频率相对时延与频率间隔、传播路径及工作频率的变化特征。分析表明短波跳频... 利用电离层斜向探测系统分别对三条短波路径进行了时延测试,在单模传播数据曲线拟合的基础上,计算了短波信道频率相对时延值,重点分析了电离层单模传播情况下频率相对时延与频率间隔、传播路径及工作频率的变化特征。分析表明短波跳频系统在单模工作时,中午时段的频率相对时延最大,跳频频点间隔越小、路径越大频率相对时延的影响越小。 展开更多
关键词 短波 斜向探测 单模传播 频率相对时延
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Fault location for parallel transmission lines using one-terminal current traveling waves
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作者 徐青山 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2009年第3期408-412,共5页
With proper phase module transformation,parallel lines can be decomposed to the same directional net and the reverse directional net. The propagation characteristics of traveling waves in the reverse directional net w... With proper phase module transformation,parallel lines can be decomposed to the same directional net and the reverse directional net. The propagation characteristics of traveling waves in the reverse directional net were analyzed,and the refraction coefficient at the fault point for a single phase fault was derived. In addition,the module selection was discussed. Simulation results show that satisfying accuracy can be achieved with the proposed method. Moreover,it is immune to fault types,fault resistances,and outside system parameters. 展开更多
关键词 fault location parallel transmission lines traveling wave reverse directional net
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Modal cutoff in rare-earth-doped photonic crystal fibers with multi-layer air-holes missing in the core 被引量:1
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作者 ZHAO Xing-tao ZHENG Yi +5 位作者 LIU Xiao-xu LI Shu-guang HANYing HOU Zhi-yun WANG Na HOU Lan-tian 《Optoelectronics Letters》 EI 2013年第3期201-203,共3页
The various mode effective indices of the doped photonic crystal fibers (PCFs) are compared, the mode field distributions of the fundamental mode and the second-order mode are analyzed, and the single-mode condition i... The various mode effective indices of the doped photonic crystal fibers (PCFs) are compared, the mode field distributions of the fundamental mode and the second-order mode are analyzed, and the single-mode condition is presented. The mode effective indices of large-core doped PCFs with different core indices and structure parameters are simulated by the finite element method (FEM). The relations of the core index with the fiber structure parameters of pitch, hole-to-pitch ratio and core diameter are obtained for single-mode propagation. In the design and fabrication of the doped PCF, we can adjust the core index and fiber structure parameters to achieve large mode area and single-mode propagation. 展开更多
关键词 光子晶体光纤 掺稀土 有效折射率 模态 气孔 结构参数 单模传播 模场分布
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Fabrication and characteristics of low loss and single-mode channel waveguides based on DNA-HCTAC biopolymer material
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作者 张飞雁 王振永 +1 位作者 颜承恩 周骏 《Optoelectronics Letters》 EI 2012年第2期97-100,共4页
A novel biopolymer, deoxyribonucleic acid-hexadecyltrimethylammonium chloride (DNA-HCTAC), is used as the core layer material in optical waveguide, and the cleanroom technology is successfully applied to fabricate the... A novel biopolymer, deoxyribonucleic acid-hexadecyltrimethylammonium chloride (DNA-HCTAC), is used as the core layer material in optical waveguide, and the cleanroom technology is successfully applied to fabricate the single-mode channel waveguides with low propagation loss. The prepared DNA-HCTAC material shows high optical quality at the optical telecommunication wavelengths, such as high transparency, relatively high refractive index and low birefringence. In the fabrication approach, polymethyl methacrylate (PMMA) is used as a barrier layer to protect the DNA-HCTAC material from the corrosive of photoresist developer, and the etching conditions are optimized to form the smooth wall and sharp cross-section of the waveguide. Lastly, the optical characteristics of DNA-HCTAC channel waveguides are measured. The results show that the DNA-HCTAC waveguide operates with single-mode propagation and has a low optical loss. 展开更多
关键词 Biomolecules Chlorine compounds Organic acids PHOTORESISTS Plasma filled waveguides Refractive index WAVEGUIDES
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