一种计算波导耦合缝隙有源阻抗的方法

 针对耦合波导缝隙馈电时波导内电磁场复杂且不利于工程应用的问题,提出一种耦合波导缝隙有源阻抗计算方法.根据耦合波导端口处S矩阵与端口处输入阻抗矩阵的关系建立关于耦合波导缝隙有源阻抗方程,且采用牛顿法求解此非线性高阶分式方程,得到计及缝隙间互耦的耦合波导缝隙有源阻抗值.通过提取HFSS软件中耦合缝隙馈电的裂缝天线S矩阵进行仿真计算,结果表明该计算耦合缝隙有源阻抗的方法是有效的且适合大型裂缝天线耦合裂缝设计.     

手征平板介质波导中的场分析

本文首次研究了手征平板介质波导中电磁波的传播特性,给出了波导中的场分布、色散关系和截止方程,以及最低截止波数Kc随手征导纳ζc的变化规律。结论表明,在手征平板介质波导中,TE、TM和TEM模均不能单独传输,其伸输模是耦合模。当ζc趋于零时,本文的所有结果均退化成通常平板介质波导情形。     

同轴TE11模与矩波导TE10模的耦合计算

首先建立同轴TE11模与圆波导TE11模的等效关系。进而将同轴TE11模与矩波导TE10模的耦合问题转化为其等效圆波导TE11模与矩波导TE10模的耦合问题。实验证明,理论计算与实测结果吻合。     

同轴TE_(11)~⊙模与矩波导TE_(10)模的耦合计算

首先建立同轴 TE1 1 ⊙ 模与圆波导 TE1 1 o 模的等效关系。进而将同轴 TE1 1 ⊙ 模与矩波导 TE1 0 模的耦合问题转化为其等效圆波导 TE1 1 o 模与矩波导 TE1 0 模的耦合问题。实验证明 ,理论计算与实测结果吻合     

双槽结构模变换器的研究

为了能够有效地分析双槽结构模变换器的传输特性,建立了由一段波纹圆波导连接的2个对称模变换器的分析模型,分析了模变换器的等效导纳特性,并由其等效导纳特性优化选取了其槽深、槽宽,深入研究了入口半径、槽数等因素对模变换器传输性能的影响,总结了各因素对模变换器驻波性能影响的规律,优选了入口半径,给出了该模变换器实现TE11模向HE11模平稳过渡所需要的槽数,结论均可用于指导工程设计.     

双圆柱体结构天线阵列的电流计算方法

在天线的设计过程中,天线表面的电流分布将对天线的性能产生重要影响。本文介绍了一种双圆柱体结构全向天线阵列的表面电流及等效端口导纳矩阵的计算方法,根据这个算法,本文计算了在一定物理尺寸下该天线阵列的电流分布和端口导纳矩阵。数值计算显示这种算法是可行的,结果是令人满意的。     

双圆柱体结构天线阵列的电流计算方法

在天线的设计过程中,天线表面的电流分布将对天线的性能产生重要影响。本文介绍了一种双圆柱体结构全向天线阵列的表面电流及等效端口导纳矩阵的计算方法,根据这个算法,本文计算了在一定物理尺寸下该天线阵列的电流分布和端口导纳矩阵。数值计算显示这种算法是可行的,结果是令人满意的。     

用直线法分析圆截面S弯管的雷达散射截面

本文首次用直线法分析计算了电大尺寸波导中本征模的截止波数及场分布函数。由此求出的直圆管RCS分布曲线,与已知的计算和测试曲线在主要关心的角度范围内吻合很好。在此基础上依据耦合波理论求得本征模在弯波导段中的传输参量,最后由Stratton—Chu积分求得S弯管的后向散射场。计算及其与测试结果的比较表明,本文方法省时、简便且有较高精度,是计算圆截面S弯管雷达散射截面的一种有效方法。     

对称带线T接头等效网络参数的计算

本文应用等效平行板波导的概念和模分析法研究了对称带线T接头的S参数。在等效平行板波导中只能传输TEM模的条件下,得到了T接头S矩阵的理论计算公式,并在频率为9.6GH_Z情况下进行了测量,理论计算与实验结果基本一致。同时与国外文献中以实验数据为基础的经验公式的计算数据作了比较,结果表明其一致性较好。     

Rotman透镜多波束形成网络的数值分析

本文利用平板波导模型法与轮廓积分方程法结合分析了一种重要的多波束形成网络－Ｒｏｔｍａｎ透镜,首先建立了考虑色散效应的透镜的等效平板波导模型,然后选择适当的波导模式展开透镜端口上的场,并利用Ｇａｌｅｒｋｉｎ法求解其边缘上电场满足的轮廓积分方程即可得到透镜的多模式散射参数,再根据网络思想,将端口存在的高阶模作为加载,从而得到主模激励的散射参数,计算结果与实验结果吻合得很好。     

An Exact Calculation for a T-Junction of Rectangular Waveguides Having Arbitrary Cross Sections

An exact method is developed for the calculation of the electrical performance of the rectangular waveguide T-junction. This method is used to find the equivalent circuit of a rectangular waveguide T-junction in which both cross-sectional dimensions of the side waveguide are different from the cross-sectional dimensions of the through waveguide. The theoretical calculations for a particular T-junction of this type are verified by experimental measurements. In this method the electrical performance is analyzed by using equivalent-circuit concepts applied to waveguide modes to calculate an admittance matrix relating propagating and cutoff waveguide modes to each other. Then the cutoff modes are terminated in their characteristic impedance, and an equivalent admittance matrix of the junction is found relating only the propagating modes in each waveguide to each other. The anlysis is valid when any number of modes can propogate in the waveguides forming the junction. The Inversion of an infinite matrix is required; however, any desired accuracy can be obtained by considering a matrix of finite but sufficient size or equivalently by considering a sufficient number of cutoff modes.     

Determination of simple equivalent circuits of interactingdiscontinuities in waveguides or transmission lines

It is well known that the generalized scattering matrix (GSM) of a microwave network, which includes one or more ports supporting evanescent modes, is nonunitary. This has hindered the formation of equivalent circuits since it has not been evident how to form the impedance or admittance matrix. This paper describes how the problem has been overcome, resulting in a method for the formation of simple equivalent circuits of interacting closely spaced discontinuities in a waveguide. The n-port immittance matrix corresponding to the nonunitary GSM is formed by normalizing the imittance matrix to real or imaginary portal impedances. As an example, an equivalent circuit for the even mode of a waveguide short-slot coupler is presented, and the effect of the evanescent TE₃₀ mode in the coupling region is clearly expressed by an evanescent-mode waveguide in parallel with one supporting the dominant propagating mode. The method should find wide applications to problems involving interactions in waveguides     

Modeling Rectangular Waveguide Junctions by the Eigenfunction Method

A method to determine the impedance and admittance matrices of a certain class of rectangular waveguide junctions is presented. First, general matrices are obtained relating all of the modes that may exist in the waveguides connected to the ports, The expressions for the matrix entries are given in terms of the eigenfunctions of the volume occupied by the junction and the fields at the ports. Second, to obtain a relationship between the propagating modes of the connecting waveguides, a numerical iterative procedure is developed to eliminate the evanescent modes from the general matrices. Practical applications have shown that the results agree well with the previous ones, and the method can readily be used to analyze different types of junctions in any required frequency range.     

A multi-port thermal coupling model for multi-chip power modules suitable for circuit simulators

This paper investigates two compact thermal model representations for multi-chip power modules, namely the thermal impedance matrix model and the thermal admittance matrix model. The latter can shape a multi-port thermal network without controlled temperature sources, and can be readily implemented in circuit simulators. The mutual transformation between the two models and their relationship to parameters in the multi-port network are revealed. In addition, practical tips for thermal model parameter extractions based on temperature measurements and curve-fitting are discussed. The multi-port thermal model is verified by simulations and experimental results. It confirms that more accurate temperature estimation can be achieved compared with the thermal model without the thermal coupling effect.     

Electromagnetic scattering from and transmission through arbitraryapertures in conducting bodies

The general 3-D aperture coupling problem is formulated in terms of an integral equation for the equivalent magnetic current in the aperture, which is numerically solved by the method of moments. The aperture is characterized by two aperture admittance matrices, one for the exterior region and the other for the interior region. These two admittance matrices are determined separately but in a similar manner if the pseudo-image method is used. Numerically workable expressions are developed for the two aperture admittance matrices by decomposing each of them into a half-space admittance matrix and a supplementary admittance matrix. The half-space admittance is relatively easy to compute and has been investigated in the literature. The supplementary admittance matrix is expressed in terms of the generalized impedance combining the existing numerical codes for an arbitrarily shaped scatterer and for an arbitrary aperture in a conducting plane, one can obtain a code which is especially designed for an arbitrary aperture in a conducting surface of arbitrary shape     

广义网络法分析复杂孔缝耦合问题

本文利用广义网络法结合连接算法分析复杂孔缝耦合问题.首先根据孔缝的结构及填充特点将其内腔体分为适当的几段,利用边界元法分别计算每段的广义导纳矩阵,再借助连接算法将各段连接起来得到整个孔缝的口径导纳矩阵,最后由广义网络法求解孔缝的口径磁流、散射及传输场.该方法不仅在计算效率方面取得了较大突破,也使复杂填充孔缝的分析得到很大简化.     

A generalized network formulation for aperture problems

A general formulation for aperture problems is given in terms of the method of moments. It applies to any two regions isolated except for coupling through the aperture. The aperture characteristics are expressed in terms of two aperture admittance matrices, one for each region. The admittance matrix for one region is independent of the other region, and hence can be used for any problem involving that region and aperture. The solution can be represented by two generalizedn-port networks connected in parallel with current sources. The current sources are related to the tangential magnetic field which exists over the aperture region when the aperture is closed by an electric conductor. Formulas for fields (linear functionals) and power (quadratic functionals) are given in terms of the admittance matrices.     

车载多天线系统的电磁兼容问题分析

本文采用矩量法和微波网络理论相结合的方法分析了车载多天线系统的电磁兼容问题，该方法先将天线系统等效为微波网络，然后采用矩量法求解该等效网络的导纳矩阵Y，利用该导纳矩阵可求得天线间的耦合度，文中也对发射功率较大的天线的近场分布进行了分析。     

Implementation of Conservation-of-Energy Condition in Small Aperture and Small Obstacle Theory (Short Papers)

In a previous paper, Felsen and Kahn showed that the scattering matrix of small apertures and obstacles in multimode waveguide regions is conveniently calculated for general lossless structures, but observed that the scattering matrix does not satisfy the conservation-of-energy requirement. It is also to be noted that the scattering parameters could become much larger than unity or even infinite for frequencies near or at the cutoff of the coupled modes. A method is presented in this correspondence to implement the lossless condition so that the resultant scattering matrix satisfies the conservation-of-energy requirement and, consequently, can be represented as a Iossless equivalent circuit for all frequencies. The corresponding impedance, admittance, and transfer matrices for general lossless symmetrical structures are given in compact form directly in terms of the scattering parameters.     

Multiport network approach for modeling the mutual coupling effectsin microstrip patch antennas and arrays

A method is described for representing the mutual coupling between edges of a microstrip patch (or the edges of two different patches in an array) in form of a mutual admittance matrix. Coefficients of the mutual admittance matrix are evaluated by modelling the edge fields by equivalent magnetic current line sources. The formulation is an extension of the multiport network modeling of microstrip patches and the segmentation method of analysis. Results are found to be in good agreement with the measured data on mutual coupling available in the literature. Relative contributions of various edges of rectangular patches to the mutual coupling are discussed