共查询到20条相似文献,搜索用时 31 毫秒
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Giuliano F. Bastista Oliveira José Elesbão C. Neto Humberto C. Chaves Fernandes 《International Journal of Infrared and Millimeter Waves》2003,24(7):1159-1169
For the microstrip patch resonator, as a planar antenna of a microstrip, a set of equations that represents the electromagnetic fields in the x and z direction as function of the electric field in the y direction are obtained applying the TTL method. This method is very suitable at microwave and antenna applications, and gives accurate complex resonant frequency, which contributes definitively to obtain higher precision antenna parameters. For each type of array is calculated the array factor, considering the excitation, phase and the relative displacement between the elements as well as the dimensions and number of elements. 相似文献
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V. V. D’yachenko M. A. Irzak E. N. Tregubova O. N. Shcherbinin 《Technical Physics》2003,48(8):1061-1066
Feasibility of rf plasma heating in the Globus-M spherical tokamak at frequencies several times higher than the ion cyclotron
frequency is considered. Results from a numerical analysis of this problem by using one-and two-dimensional codes are presented.
It is shown that, for the plasma parameters attainable in this device, the single-pass absorption of fast magnetosonic waves
reaches 60%. The energy is released near the plasma axis. The radiation resistance of a one-loop antenna should be close to
1 Ω. The design of an antenna that allows one to match the rf oscillator to the load is described. The parameters of the antenna
resonator required for optimum operation of the antenna are given. 相似文献
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Z. H. Qian R. S. Chen Z. H. Fan P. L. Rui 《International Journal of Infrared and Millimeter Waves》2008,29(5):486-492
A gaseous plasma column as an efficient radiator of electromagnetic waves is well known. This paper presents the scattering
analysis of a plasma antenna using the conjugate gradient fast Fourier transform (CG-FFT) method. Radar cross sections (RCS)
of designed plasma antenna for different plasma parameters are computed mainly. Numerical results show that the plasma antenna
with appropriate parameters can offer lower RCS than the metal one. It is evident from the observed scattering characteristics
that the plasma antenna can be regarded as a rod of imperfect conductor with losses. 相似文献
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黄冶 《核聚变与等离子体物理》2015,35(2):103-108
建立了等离子体-绝缘管-真空结构的等离子体天线物理模型,推导了新的色散关系方程,通过几何诠释,给出了一种新的高精度快速收敛求解方法,计算机仿真验证了结论的正确性和有效性。利用算法研究了当电子密度按线性律减小时,圆柱等离子体天线的色散关系,并绘制了方向图。这些结果对等离子体天线的分析与设计具有重要的参考价值。 相似文献
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黄冶 《核聚变与等离子体物理》2015,35(2):103-108
建立了等离子体-绝缘管-真空结构的等离子体天线物理模型,推导了新的色散关系方程,通过几何诠释,给出了一种新的高精度快速收敛求解方法,计算机仿真验证了结论的正确性和有效性。利用算法研究了当电子密度按线性律减小时,圆柱等离子体天线的色散关系,并绘制了方向图。这些结果对等离子体天线的分析与设计具有重要的参考价值。 相似文献
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基于天文观测的相机标定及姿态测量技术研究 总被引:1,自引:0,他引:1
为利用相机进行天文观测以实现高精度的相机姿态测量,必须先对相机参数进行精确标定。针对传统相机标定方法工作距离有限的问题,提出了以恒星为控制点的相机标定方法,根据球面天文学方法计算观测时刻控制点的世界坐标,利用摄像测量原理建立了恒星观测模型,求解相机的内外参数并分析了误差因素。实验结果表明,该标定方法在不依赖于精密、复杂的外部设备情况下可达到较高精度,并具有较强的抗噪声能力。将标定结果用于天文观测并求解相机姿态,航向角和俯仰角的解算重复性优于10″,能够满足高精度姿态测量的需求。该方法可进一步推广应用于星敏感器的标定。 相似文献
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离子回旋共振加热的耦合计算 总被引:1,自引:2,他引:1
托卡马克离子中回旋共振加热(ICRH)的平板模型在计算沿极向尺度较长的天线时误差较大,针对这一问题提出了一种将天线进行分段处理的改进算法,该算法提高了计算精度,计算结果表明,天线越长,改进算法的计算精度改善越明显。 相似文献
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This paper reports the design and analysis of a novel helix antenna based on Micro-electromechanical Systems (MEMS) technology, which is used in terahertz (THz) applications. The structure of the antenna includes two parts, the metallic helix and the coplanar waveguide (CPW) on the substrate for feed, the fabrication of the structure needs only one wafer, and the antenna can be easily integrated with other parts of on-chip circuits. There are many tunable parameters of the helix, so that high performance THz antenna can be achieved by optimizing these parameters. The proposed antenna can be manufactured by MEMS processing with low fabrication cost, suitable for many terahertz systems. 相似文献
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脉冲星星历表维持着脉冲星导航所需的时空基准, 其精度直接影响着航天器导航定位结果, 是脉冲星导航系统的基本要素. 本文分析了脉冲星空间观测精度的估计方法, 探索性地研究了基于空间X射线观测获取星历表参数的可行性. 通过建立星历表参数拟合模型, 采用大样本重复事件仿真分析了空间X射线观测精度, 研究了星历表参数确定精度与观测精度、观测时间及观测频次的关系. 研究结果表明, 空间X射线观测可以确定脉冲星星历表参数, 但受限于脉冲星信号特征及探测器技术水平, 当前高精度导航用脉冲星星历表难以通过空间X射线观测手段获得, 可通过地面射电观测技术较好地建立与维持, 提出了推进我国大口径射电望远镜建设的建议. 相似文献
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基于射线跟踪模型,提出了一种超材料角反射面结构,实现了Fabry-Perot天线增益和口径效率的提升.首先对基于超材料角反射面的Fabry-Perot天线进行了理论推导和分析.然后,设计并分析了双圆极化馈源、基于超材料角反射面的Fabry-Perot天线及其性能.最后,对所提出的Fabry-Perot天线模型进行了制造和测试.结果表明,该天线的左圆极化增益和右圆极化增益分别为21.4 d Bi和21.3 d Bi.相比馈源天线,增益分别提高了16.4 d B和16.3 d B.与传统Fabry-Perot天线相比,所提出超材料角反射面同时充当了反射面和相位校正面,实现了对Fabry-Perot天线边缘电磁波的有效调控.所设计Fabry-Perot天线工作在2.8 GHz频段,具有高增益、高口径效率和低旁瓣的优点,满足了太阳射电望远镜F107指数观测的需求. 相似文献
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C. F. L. Vasconcelos M. R. M. L. Albuquerque G. M. F. Freitas A. G. D’Assunção 《Applied Physics A: Materials Science & Processing》2013,111(4):1085-1089
The annular ring microstrip antennas on metamaterial substrates are modeled and analyzed using full-wave analysis in conjunction with Ansoft HFSSTM. The influence of the permeability tensor of the split ring resonator medium on the resonant characteristics of the antenna is considered. Numerical results for typical resonant frequency behavior and return loss are presented as function of the metamaterial properties and antenna structural parameters. 相似文献
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G. S. Malyshkin 《Acoustical Physics》2014,60(3):309-322
This paper presents results on evaluating the impact of a set of physical and technical factors on the effectiveness of classical and projection fast adaptive algorithms. The factors include the conditions of signal propagation, including multipath; the noise-signal situation; signal fluctuations due to scattering in the medium; the parameters of the receiving antenna, including the amplitude-phase value of element dispersion; and the parameters of the spectral signal analysis at the output of the antenna elements. 相似文献
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Hengzhen Jing Shanjia Xu 《International Journal of Infrared and Millimeter Waves》2002,23(7):1079-1089
A new millimeter-wave omni-directional antenna consisting of circular rod corrugations gloved with a dielectric shell operating in the TM01 mode is investigated. As an eigenvalue problem, the antenna is analyzed with the rigorous mode matching method. The radiation characteristics of the antenna are calculated for different parameters with a particular attention directed to the Brewster angle effect on the performances of the antenna. A comparison of the radiation characteristics is made between the antennas with and without dielectric shell. It is found that the introduction of the dielectric shell will change the location where the leakage constant reduced to zero. The effectiveness and reliability of the present analysis are verified by the calculated results given in the literature. Therefore, some useful guidelines for the design of the antenna are thereby suggested. 相似文献
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采用时域有限差分方法计算了银纳米圆盘光天线模型的场分布,研究了光偶极天线的远场辐射特性随距离和厚度、半径变化的规律以及影响其远场方向性的因素.研究发现,偶极子垂直放置在银纳米圆盘下方一定距离时,银盘厚度和半径的改变均可使方向性图中出现新的辐射模式,同时方向性增益得到增强.通过对其近场的观察和分析可以得知,新的辐射模式的产生来源于高阶模式的局域表面等离激元.结果表明,背景材料为GaN时,产生高阶模式局域表面等离激元的合适条件为电偶极子距银盘底部40nm.另外,为了有效地支持高阶模式局域表面等离激元的形成,银盘厚度与半径最小分别为30nm和100nm.本文的研究对掌握纳米银盘结构的光天线特性及其在光器件中的运用有重要意义. 相似文献
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采用时域有限差分方法计算了银纳米圆盘光天线模型的场分布,研究了光偶极天线的远场辐射特性随距离和厚度、半径变化的规律以及影响其远场方向性的因素. 研究发现,偶极子垂直放置在银纳米圆盘下方一定距离时,银盘厚度和半径的改变均可使方向性图中出现新的辐射模式,同时方向性增益得到增强.通过对其近场的观察和分析可以得知,新的辐射模式的产生来源于高阶模式的局域表面等离激元. 结果表明,背景材料为GaN时,产生高阶模式局域表面等离激元的合适条件为电偶极子距银盘底部40 nm. 另外,为了有效地支持高阶模式局域表面等离激元的形成,银盘厚度与半径最小分别为30 nm和100 nm. 本文的研究对掌握纳米银盘结构的光天线特性及其在光器件中的运用有重要意义. 相似文献
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In this work, the operating parameters of the plasma antenna are optimized using a kinetic model based on Particle in Cell‐Monte Carlo Collisions (PIC‐MCC) method. This optimization study is performed via the investigation of variations in the operating parameters of the plasma antenna, i. e., its dimensions, background gas pressure, and the applied voltage frequency and their consequent effects on the plasma frequency, kinetic energy of electrons and plasma current density of plasma antenna. While the antenna performance is improved at higher tube lengths and applied frequencies, it is optimized at a particular tube radius. Moreover, higher background pressures have increasing effects on the plasma antenna operation. Based on this parametric study, the optimum operating parameters of the plasma antenna are established. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献