共查询到20条相似文献,搜索用时 93 毫秒
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研究了同轴传输线中金属光子晶体的电磁特性,在此基础上优化了一种适用于窄带高功率微波源系统的金属光子晶体TEM-TE11模式转换器。该结构通过沿传输线角向部分填充的金属光子晶体实现移相。采用数值仿真程序对L波段模式转换器进行计算,在1.57GHz中心频率上,模式转换器转换效率为99%;在1.533~1.609GHz频率范围内,模式转换器效率大于90%,相对带宽4.8%。加工了TEM模式激励器和辐射天线,并在微波暗室对模式转换器进行了小信号测试,验证了模式转换器的性能。 相似文献
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与介质光子晶体相比,金属光子晶体的带隙特性在毫米波和亚毫米波波段有着重要的应用价值.基于Yee网格的频域有限差分法推导得出的本征模方程,求解后能方便而又可靠地得出介质光子晶体的带隙图和场分布.但由于金属与介质的本质差异,该方法不能直接应用于金属光子晶体.文中引入了金属表面边界条件,推导了二维金属周期结构的光子带隙本征模方程.通过数值计算,得出了不同晶格结构(正方/三角格子)下两种模式(TE/TM)的全禁带特性,并与介质周期结构的禁带特性进行对比,分析了金属周期结构在模式选择和器件集成方面的优点.
关键词:
金属光子晶体
频域有限差分法
全禁带 相似文献
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传统光纤中的光能损耗和色散是阻碍其进一步向大容量和远距离通信方向发展的主要原因,因此制造具有低色散和低损耗的光子晶体光纤成为光纤技术努力的方向。在介绍光子晶体光纤的制作、导光原理和特点的基础上,研究了普通光纤不具备,而光子晶体光纤所具有的无休止的单模特性、奇异的色散特性、可控的非线性和易于实现的多芯传输等特点。研究结果表明,光子晶体光纤在光纤传感器、光子晶体天线、超宽色散补偿、光学集成电路等多方面具有广泛的应用前景。 相似文献
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与介质光子晶体相比,金属光子晶体的带隙特性在毫米波和亚毫米波波段有着重要的应用价值.基于Yee网格的频域有限差分法推导得出的本征模方程,求解后能方便而又可靠地得出介质光子晶体的带隙图和场分布.但由于金属与介质的本质差异,该方法不能直接应用于金属光子晶体.文中引入了金属表面边界条件,推导了二维金属周期结构的光子带隙本征模方程.通过数值计算,得出了不同晶格结构(正方/三角格子)下两种模式(TE/TM)的全禁带特性,并与介质周期结构的禁带特性进行对比,分析了金属周期结构在模式选择和器件集成方面的优点. 相似文献
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一维金属/介质光子晶体用于BaF2晶体闪烁光谱修饰 总被引:14,自引:6,他引:8
利用一维金属/介质光子晶体对BaF2晶体闪烁光谱进行修饰. 以Al2O3/MgF2/Al/ MgF2为周期构成光子晶体,讨论了周期数、金属层的厚度以及在低折射率层中的相对位置、入射角度等与光子晶体能带特性的关系及其对BaF2晶体闪烁光谱进行修饰的效果. 结果表明,在所考虑的发射角范围,光子晶体对快成分的衰减小于5倍,对慢成分的相对抑制比超过20倍,采用合适的探测角度,可使对慢成分的相对抑制比提高到100以上. 相似文献
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Planar microstrip patch antennas can achieve a wide range of radiation patterns. However, due to surface-wave losses, they have low bandwidth, low gain, and a potential decrease in radiation efficiency. In order to minimize the surface-wave effects, a photonic-band gap (PBG) substrate is proposed. The PBG structure significantly diminishes the surface-wave modes and thus improves the gain and far-field radiation pattern and efficiency. In this paper, using FDTD, an accurate full-wave analysis of surface-wave propagation in a rectangular microstrip patch antenna with and without PBG is presented. Finally, the antenna fabricated and result of measurement was compared with numerical simulation. 相似文献
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本文描述一种新颖的ECRF天线,简述了它的原理及所进行的实验。基于互逆性原理,首先利用Vlasov天线的逆过程获得了一个圆模式输出的测试用微波源。在此基础上,对该天线的正过程进行了实验与测试,得到了几乎完全线极化的天线辐射场分布。并将实验结果与理论结果进行了比较与分析。 相似文献
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使用频域矩量法(MM)和时域有限差分方法(FDTD)对VLASOV天线进行了系统研究。通过数值模拟:对VLASOV天线中的模式转换及其辐射过程进行有了清晰的物理描述;对VLASOV天线进行了参数化研究;并为实验提供了加工原型,实测结果与模拟结果吻合良好。在此基础上,结合VLASOV天线在高功率微波系统中的应用提出了一种新的设计方案。该方案实现了天线与天线罩的一体化设计,使辐射波束实现了较好的圆对称性,天线增益提高6dB,第一副瓣电平下降13dB。 相似文献
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C. Deng J. W. Haus A. Sarangan A. Mahfoud C. Sibilia M. Scalora A. Zheltikov 《Laser Physics》2006,16(6):927-947
Enhanced second-harmonic generation (SHG) conversion efficiency was theoretically predicted in waveguide geometry with coupling to a one-dimensional grating photonic band gap (PBG). We report a series of experiments using samples made with lithium niobate. A waveguide was fabricated near the surface by applying the proton-exchange technique. The characteristics of waveguide modes were determined by several techniques: prism coupling, diffraction, and Cherenkov radiation. The WKB method was used to analyze the results. Ultraviolet laser lithography was applied to make PBG gratings on the sample. We further investigated Cherenkov second-harmonic generation (CSHG), i.e., SHG radiated into the substrate, under the condition of a band-edge PBG resonance in the waveguides. The SHG inside planar waveguides was also experimentally investigated. We fabricated waveguides with multiple pump modes and found that the second mode was more efficient in enhancing the second harmonic signal. This result is explained by our model. Several samples were investigated in detail; the highest conversion efficiency of CSHG with a PBG was enhanced around 50 times above the CSHG signal without a PBG. A numerical model was constructed with parameters calculated from our sample characterization data to interpret the experimental results. 相似文献
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Shen Ting-gen Zhou Yue-qun Ge Jun Yu Feng-chao Ji Pei-lai Wang Gang 《Journal of Russian Laser Research》2008,29(3):255-261
The method of finite-difference-time domain (FDTD) was used to study the characteristics of the patch antenna based on drilling
air holes in the PBG substrate. The results obtained show that the waves propagating along the substrate surface can be suppressed
by the drilled photonic crystal band gap (PBG) structure due to the influence of its forbidden band. The energy of the electromagnetic
waves is concentrated mainly in the substrate. As a result, patch antennas based on drilling air holes in the PBG substrate
have lower return losses (S11) in comparison with the conventional patch antennas; thus, a high gain is reached and the performance
is improved. Due to such the advantages, the use of patch antennas can be extended to such fields as mobile communication,
satellite communication, aviation, etc. 相似文献
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提出了一种新型的具有光子晶体带隙(PBG)结构的返波振荡器(BWO),利用PBG禁带对BWO工作及输出微波模式进行调制,抑制低次模式,工作在高次模式。通过数值模拟给出了介质柱PBG结构的能带图、禁带限制模式电场分布和周期慢波结构的色散关系曲线,选择晶格常数为0.31 cm,介质柱半径为0.12 cm,介电常数为4.0的三角格子PBG结构可以实现在Ka波段的单一类TM03模式工作,在36~40 GHz的频率范围内,器件可以工作在返波状态,周期长度为0.4 cm。 相似文献
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GYROTRON III is a cw source of near-millimetre wave radiation that is tunable over the frequency range 75 to 330 GHz. The high-order waveguide modes that are characteristic of tunable gyrotrons are converted into a well-collimated, linearly-polarized beam by means of a quasi-optical or Vlasov antenna. 相似文献
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K. X. Jin S. G. Zhao X. Y. Tan C. L. Chen X. W. Jia 《Applied Physics A: Materials Science & Processing》2009,95(3):789-792
We used the method of finite-difference time domain (FDTD) to study the characteristics of the patch antenna based on a novel
periodic structure, and the theory of photonic crystal structure (also photonic band gap [PBG]) structure was introduced.
The results obtained show that the surface waves propagating along the substrate surface can be suppressed by the periodic
structure due to the influence of its forbidden band, and the energy of the electromagnetic waves is concentrated mainly in
the substrate. As a result, the patch antenna based on the periodic structure has a wider bandwidth in comparison with the
conventional patch antennae; and a higher gain is reached, so the patch antenna’s performance is improved. Due to such the
advantages, the application of patch antennae can be extended in such fields as mobile communication, satellite communication,
aviation, etc. 相似文献
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Chunheng Liu Yueguang Lu Chunlei Du Xiangang Luo 《International Journal of Infrared and Millimeter Waves》2007,28(12):1115-1122
A aperture-coupled patch antenna is designed with parasitic elements connecting to the rectangle ring on the bottom of antenna
substrate through metal vias, which lead the current induced by patch radiator to the top surface of antenna substrate. Therefore,
the effective radiation is enhanced and higher gain is achieved. The bandwidth is broadened simultaneously due to the structure
of aperture-coupled patch antenna with parasitic elements. Compared to the conventional aperture-coupled patch antenna, the
antenna gain increases averagely 2 dB due to the novel structure. Compared to patch antenna of electromagnetic band-gap, the
dimensions of novel patch antenna greatly decreases, which can be used as element in the array antenna. Two kinds manufactured
antenna are both measured in an anechoic chamber. The good agreements between numerical simulation and experimental prototype
have been obtained. 相似文献