用非均匀网格FDTD法分析介质填充波导和微带线的传输特性

【作者】 姜艳娥；

【导师】 郑勤红；

【作者基本信息】 云南师范大学 ， 无线电物理， 2009， 硕士

【摘要】 本文主要开展非均匀网格FDTD方法在波导和微带线问题中的应用研究,基于非均匀网格法结合Matlab编写了相关计算程序,对多种场域条件下的波导和微带线进行了模拟计算,分析了其相关物理参数或模场特性。首先,简要综述了各类电磁场问题的常用求解方法,对FDTD方法的发展历程和基本原理进行了综述性分析;结合文献和编程计算经验,阐述了FDTD方法的数值稳定性和数值色散对空间网格和时间步长的要求、介质分界面的处理方法、吸收边界的设置方法以及激励源的选择与设计。基于FDTD方法的数值稳定性和数值色散对空间网格和时间步长的要求,推导出非均匀网格FDTD方法的网格划分公式。其次,提出用非均匀网格FDTD法计算了部分介质填充矩形波导、部分介质填充双脊波导、部分介质填充三脊波导和部分介质填充非对称脊波导的截止频率,并将计算结果与相关文献的报道结果进行了比较,证明了方法和所编程序的正确性。计算结果表明:非均匀网格FDTD法比均匀网格FDTD法的运行时间节约了10%-20%。最后,提出用非均匀网格FDTD法分析计算了微带线的特性阻抗及高次模的截止频率。首先用非均匀网格FDTD法计算了矩形-微带内导体同轴传输线、标准微带线、倒置微带线和双带线的特性阻抗,并与相关文献进行了比较,计算结果表明:非均匀网格FDTD法比均匀网格FDTD法的运行时间节约5%-20%。此外还用非均匀网格FDTD法比均匀网格FDTD法计算了屏蔽微带线的各高阶模式的截止特性,并对所作图形进行分析推测。更多还原

【Abstract】 In this paper, research work on the application of Non-uniform FDTD method in waveguide and microstrip line is carried out. The relative programs are made based on non-uniform grid FDTD method and the Matlab. The electromagnetic fields of the waveguide and microstrip line in different conditions are simulated and calculated. Also some important physics parameters and the mode fields are obtained.Various methods to analyze electromagnetic field problems are introduced. The development and basic theory of FDTD method are synthetically analyzed. The requirements for the time interval and spatial condition for stability of FDTD method based on different boundary and optimization design excitation sources in making programs are discussed. The formula of non-uniform mesh FDTD method is also derived.Based on non-uniform FDTD method, the cutoff frequencies of rectangular waveguide partially filled with dielectric are calculated. And the cutoff frequencies of the double- and tri-ridged waveguide, and unsymmetrical ridged waveguide partially filled with dielectric are also calculated. The results agreed well with that of the reported in the literature. It has been shown that non-uniform FDTD method can economize on running time 10%-20%.Based on the non-uniform FDTD method, the characteristic impedance and high-order mode cutoff frequencies of microstrip line are calculated. First the characteristic impedance of rectangle-microstrip line, the standard microstrip line, inverted microstrip line, and double-microstrip line are calculated by non-uniform FDTD method. The results agree well with that of the reported in the literature. It has been shown that non-uniform FDTD method can economize on running time 5%-20%. The high-order mode cutoff frequencies of microstrip line are calculated, and the change curves are also obtained.更多还原