Three-Dimensional FDTD Analysis of Chiral Discontinuities in the Waveguide

A simple finite difference time domain (FDTD) scheme for chiral media is developed for modeling the chiral discontinuities in the waveguide with the aid of the second-order backward finite difference. The accuracy of the FDTD scheme is demonstrated by the comparison between our calculated results and those in the literature for achiral and chiral media. Comparisons of characteristics between chiral and achiral discontinuities in the waveguide are presented at last.     

矩形波导不连续性的有限元分析

本文应用Gelerkin有限元法对矩形波导H面和E面不连续性问题进行了研究,编制了一个通用的计算机程序.对矩形波导H面弯曲、E面弯曲以及T型结头进行了计算机辅助设计,理论计算与测试结果吻合很好,证明了本文方法的正确性.     

用于杂波抑制滤波器优化设计的混合遗传算法 及其收敛性分析

参差时变动目标显示(MTI)滤波器是在强运动杂波背景下检测弱目标和缓解盲速问题的一种有效方法.选择适当参差码使参差时变MTI滤波器的第一零点尽可能浅,可在有效抑制杂波的同时避免陷入其中的弱目标丢失.本文采用了结合梯度的混合遗传算法(HGA)选择最优参差码,与标准遗传算法(SGA)相比,该算法只需要很小的种群规模.采用马尔可夫链方法证明了HGA是以概率1收敛的全局随机搜索算法.将该算法应用于米波雷达中,性能分析和仿真实验表明,基于混合遗传算法的杂波抑制滤波器设计是可行和有效的.     

一种分析波导系统不连续性的数值计算方法

本文介绍一种分析波导不连续性的数值计算方法 ,采用有限差分法和共轭梯度法对根据矢量偏微分算子理论得出的电磁波基本方程进行求解 ,由此计算出反射系数和传输系数 ,文中以加载金属膜片的矩形波导为例说明了这一计算过程     

Solution of Waveguide Discontinuities by Modal Analysis

A general method is presented for analysis of waveguide junctions and diaphragms by summing normal modes of propagation, giving solutions for the resulting scattered modes. Because interaction effects of dominant and higher-order modes between discontuities are allowed, finite-length obstructions can be studied. Solutions are found without any prior assumption about the total fields existing at the discontinuities and, as a result, the formulation is applicable to a wide range of problems. The technique proves to be simple and is ideally suited to computers, involving mainly the solution of sets of simultaneous linear equations. Thick and thin symmetrical bifurications of a rectangular guide are studied. Forward-scattered mode amplitudes and imput admittances are calculated, the computed admittance of the thin bifurication is compared with well-known results, and transverse field patterns on both sides of the junction are plotted, thus showing the accuracy of the match. The results of a finite-length bifurication by a thick vane are presented for a range of lengths, the parameters of the equivalent T network being given in each case. For very short lengths, the problem corresponds to an inductive strip across the guide.     

波导不连续线性的直线法分析

本文利用谐振原理和求解场分布的方法,将直线法稚广应用于波导不连续性问题的分析,对矩形波导E面拐角、E面阶梯及感性膜片等不连续性的等效电路参量进行了分析计算,数值结果与有关文献的结果一致。本文所述方法具有分析过程简单,计算量小的优点。     

Transmission Matrix Representation of Finline Discontinuities

A general treatise of cascaded discontinuities in inhomogeneous waveguides is given and applied to finline circuits. A transmission matrix representation is superior to a scattering matrix representation as far as CPU time is concerned. The scattering matrix is, however, advantageous if the sum of the line lengths separating the discontinuities is large. Numerical examples are given in order to illustrate the effect of increasing the number of modes used to represent the field at both sides of the discontinuity.     

平板介质波导不连续性问题的边界元法分析

本文应用边界元法分析了不对称平板介质波导不连续性结构的散射特性,编制了一个通用的计算机程序,对几个算例进行了计算,结果与已发表文献一致。     

介质加载大功率消失模滤波器的设计

针对腔体滤波器低气压下容易发生大功率击穿的难题,提出了一种局部加载介质的消失模结构,可以有效避免滤波器低气压放电。设计了一款X波段宽带大功率消失模滤波器,利用三维仿真工具进行仿真优化,并根据电磁场仿真结果计算低气压击穿功率阈值。对制作的样品进行了性能测试,测试特性曲线与仿真曲线吻合;同时,进行了低气压功率试验,样品通过了300 W低气压(1 000~1 mbar)功率试验。通过该方法设计制作的消失模波导滤波器具有宽带匹配性能良好、Q值高、损耗小和低气压击穿功率阈值高等特点。     

Discontinuities in a Rectangular Waveguide Partially Filled with Dielectric

The modal spectrum for a rectangular waveguide with a dielectric slab at the bottom of the guide is obtained following the Characteristic Green's Function method developed by Marcuvitz. Then a four-terminal network is found as equivalent to the junction of the partially filled waveguide and an empty rectangular waveguide. An integral equation is written for the electric field at the plane of the junction and variational expressions are derived for the parameters of the four-terminal network connecting the transmission line equivalent to the partially filled waveguide to the transmission line equivalent to the empty guide. A reasonable guess for the electric field at the discontinuity gives approximate values for the parameters of the four-terminal network. These values agree with experiment. The parameters of the network are plotted vs frequency and thickness of the slab.     

阶梯波导的传输矩阵研究

用模式匹配方法分析H面阶梯波导的TE模式,首先将各区域的场写为x函数矩阵与z函数矩阵以及本区域的场系数向量相乘的形式,然后对相邻区域的x函数矩阵进行加权积分得到矩阵形式的匹配方程组。不仅在表达形式上简洁紧凑,而且能够方便的推导出考虑高次凋落模的传输矩阵。通过传输矩阵求解场,未知数个数成倍减小,运算量显著降低。数值例子验证了方法的正确性。     

基于消失模耦合的脊波导滤波器设计方法

针对传统脊波导滤波器设计中没有考虑耦合结构频率特性导致设计精度不高的问题,文中提出了一种基于消失模耦合的脊波导滤波器设计方法。该方法将工作于消失模状态下的矩形波导结构等效为频变阻抗变换器模型,通过等效电路变换将耦合结构的频变特性影响转换为对传输线谐振腔电抗斜率参数的影响,采用逐级仿真策略确定滤波器结构尺寸,避免了耗时的全波仿真优化。最后,通过一个4阶切比雪夫特性的脊波导滤波器设计实例进行验证。全波仿真结果显示了与理论设计相同的通带内等波纹特性,验证了所提方法的有效性。     

Resonant Modes in Waveguide Windows

Analysis and experimental verification of a class of resonant fields, called ghost-modes, occurring in waveguide dielectric windows are presented. Numerical solutions for a simple geometry are given through universal curves. Knowledge about ghost-modes has importance to designers of high-power windows. It also leads to a measuring technique for dielectric constants through a frequency measurement.     

椭圆波导中的本征模

在椭圆波导的应用中，场量和场图是非常有用的。本文采用将马丢函数展成傅里叶级数的方法，讨论了椭圆波导中的场分布，给出了偏心率E＝0．75时前100个模的场图。这些具有完整电磁力线的场图是严格的和标准的，力线的疏密程度正比于该处的场强。     

Waveguide Modes Via an Integral Equation Leading to a Linear Matrix Eigenvalue Problem

A numerical method for determining the modes of a rectanguIar or a circular waveguide strongly perturbed by axial cylindrical conducting objects is presented. The method is based upon an integral equation which leads to a matrix eigenvalue problem by using the Galerkin procedure. Cutoff wavenumbers are simultaneously calculated with very good precision for a number of modes near to the order of the matrix eigenvalue problem. Excellent results are obtained also when the perturbed waveguide section exhibits reentrant parts or edges. Computing time is short and storage requirements are moderate. The method is also applicable for waveguides of arbitrary cross section.     

Network Representation for Lossless Symmetrical Discontinuities in a Multimode Waveguide

It is shown that a symmetrical, lossless 2N-port may be represented by an equivalent circuit, a 2N-port lattice network, which is a 2N-port generalization of the known two-port symmetrical lattice. The approach employed here in finding the equivalent circuits is based on the fact that any symmetrical 2N-port may be decomposed into two general N-port networks, each of which represents the opencircuit or short-circuit bisected structures.     

利用矩阵法分析一维非均匀矩形波导的LSE模特性

我们利用矩阵方法建立了一维非均匀填充矩形波导的传播特性方程。在均匀情况下,本方法推出的结果与精确分析解完全一致,并对一些非均匀结构进行了数值计算,给出了一些曲线。     

A Practical Method of Locating Waveguide Discontinuities (Correspondence)

In the maintenance of ultra-high frequency equipments utilizing waveguide, one of the more difficult troubles to diagnose and correct is that of the high standing wave ratio. The question always arises as to whether the antenna or the waveguide is at fault. Sometimes a visual inspection of the transmission system will disclose the difficulty. Too often, however, the physical layout of the system makes a close inspection impractical. The construction of many antennas, also, does not permit an examination of the radio frequency components without a complex mechanical disassembly, costly in terms of man-hours.     

Analysis of Waveguide Discontinuities by a Fourth-Order Finite-Difference Reflective Scheme

A highly accurate reflective scheme is developed for analysis of two-dimensional (2-D) waveguide discontinuities by using the fourth-order finite-difference (FD) formula. It is demonstrated that the new method achieves a significantly higher accuracy/computation cost ratio in comparison with the conventional FD method. Furthermore, the advantage of the new method is more pronounced for the case of high-index-contrast structures with small feature sizes