Analysis of the Microstrip and the Electrooptic Light Modulator

Green's function for examples with an isotropic media is obtained using the image-coefficient method. The method is based on the boundary conditions and the reciprocity relation. Using this Green's function and solving directly the charge distribution on the strip, the line capacitances per unit length of a microstrip and of an electrooptic light modulator are obtained. High accuracy of this method is demonstrated by comparing the present results with the results obtained using the conformal mapping and with other data appeared in the literature. The charge distributions are also illustrated. Of particular interest is the effective filling fraction of the dielectric material, which depends mainly on the shape ratio and only slightly on the relative dielectric constant. The effective filling fractions are tabulated for the microstrip with a homogeneous dielectric substrate.     

An efficient algorithm for the three-dimensional analysis ofpassive microstrip components and discontinuities for microwave andmillimeter-wave integrated circuits

A numerical technique for the full-wave analysis of shielded, passive microstrip components on a two-layer substrate is presented. The distinct feature of the technique is an efficient formulation for establishing the system matrix in the moment method procedure which allows the derivation of the elements of any large matrix by a linear combination of elements in a precomputed index table. The table is obtained from a two-dimensional discrete fast Fourier transform. In the moment method procedure, the two-dimensional surface current is represented by locally defined rooftop functions. The effect of the resonant modes associated with the metallic enclosure on the numerical procedure is examined. In order to demonstrate the features and the accuracy of the technique, numerical results for a microstrip open end and for a right-angle bend with and without the compensated corner are computed by using the resonant technique and are compared with other published computational and experimental data     

Accurate characterization of planar printed antennas usingfinite-difference time-domain method

The finite-difference-time-domain method (FD-TD) is used to characterize complex planar printed antennas with various feed structures, which include coaxial probe feed, microstrip line feed, and aperture coupled feed structures. A coaxial probe model is developed by using a three-dimensional FD-TD technique. This model is shown to be an efficient and accurate tool for modeling coaxial line fed structures. A novel use of a dispersive absorbing boundary condition is presented for a printed antenna with a high dielectric constant. All the numerical results obtained by the FD-TD method are compared with experimental results, and the comparison shows excellent agreement over a wide frequency band     

Analysis of arbitrary shape printed line microstrip antennas

A rigorous solution for arbitrary-shape printed line antennas is developed using the microstrip Green's functions. The current distribution of the line is determined by a moment method and the use of sinusoidal basis functions. Analytical expressions for the far zone fields are obtained using an asymptotic method for evaluating the Sommerfeld integrals. Examples illustrating the accuracy of the method and characteristics of selected printed antennas are presented. It is found that, for undulated printed line elements, the resonance length increases when the undulation height increases. Various examples of undulated printed line elements which are useful for array design are investigated. The effect of the undulation height on the radiation characteristics of the printed line is studied     

Hybrid-mode analysis of multilayered and multiconductortransmission lines

Hybrid-mode propagation properties of multilayered and multiconductor transmission lines are studied by using an efficient vector finite element method (FEM) with high-order hybrid edge/nodal triangular elements, which can give frequency-dependent propagation constants directly. Characteristic impedances are also calculated from the FEM field solutions employing a reciprocity-related definition and taking the modal orthogonality into account. The numerical results of a coupled microstrip line are compared with those of the boundary integral equation technique, and good agreement is obtained. Also, a dual-plane triple microstrip line is analyzed. The approach is found to be very general and able to simultaneously handle different thicknesses and widths of strip conductors. The flexibility of the approach is also shown by including anisotropy in the dielectric substrates of such lines     

On the use of differential equations of nonentire order to generateentire domain basis functions with edge singularity

Entire domain analytical basis functions with edge singularity are a very useful tool for analysing planar transmission lines and planar rectangular or circular circuits in a moment method solution. Analytical basis functions are limited to separable geometry. In this paper we introduce new entire domain basis functions including edge singularity at the edges of a domain with arbitrary shape. These basis functions are derived from a differential equation of nonentire order which includes a fractional derivative. The one dimensional case is considered first. In the two dimensional case the basis functions are constructed numerically using the boundary element method and the Galerkin method. The basis functions are applied in a moment method solution to analyse a shielded microstrip. The current and the electric field are calculated and compared with the results obtained by analytical basis functions     

Analysis of a shielded microstrip line with finite metallizationthickness by the boundary element method

A boundary element method is presented for the quasi-static analysis of a shielded microstrip line with finite metallization thickness. The analysis is based on the solution of a system of boundary integral equations which are derived from Green's second identity. Numerical results for the charge distribution along the strip and the effects of metallization thickness on line characteristics are presented. The results show good agreement with data available in the literature     

网络分解直线法结合周期边界条件分析开域微带结构

本文用网络分解直线法结合周期边界条件,以平面波激励,通过贴片电流提取相关参数的方法,分析开域微带结构。阻抗元素计算和减缩方程求解,分别使用快速傅里叶变换和网络分解技术,从而大大提高了计算效率。周期边界模拟开域的收敛性研究和计算时间的比较表明了该方法的有效性。最后计算了矩形贴片平面谐振器的谐振频率,其结果与已发表的值吻合很好。     

Rectangular resonators in inverted microstrip and suspended microstrip

Resonant frequency characteristics of rectangular resonators in a generalized shielded suspended substrate line are analysed using a rigorous spectral domain technique. The computed dominant mode resonant frequency of rectangular resonators in a suspended microstrip with centred dielectric, inverted microstrip and suspended microstrip are presented as a function of various structural parameters. These characteristics are distinct from those obtained for a conventional microstrip rectangular resonator. Experiments are carried out in the frequency range 4-18 GHz to verify the computed resonant frequencies for a suspended microstrip with a centred dielectric using first-order basis functions. The results should find applications in the design of inverted microstrip and suspended microstrip passive microwave and millimetre wave integrated circuits.     

Dynamic analysis of a microstrip line over a perforated groundplane

A full wave analysis is presented to compute the characteristic impedance and propagation constant of a microstrip line over a perforated ground plane. The perforations in the ground plane are modeled by equivalent magnetic currents. The method of moments is applied to solve the coupled integral equations for the unknown electric current on the microstrip line and the unknown magnetic currents in the apertures. The fields are formulated using the space domain Sommerfeld type Green's functions. The matrix pencil technique is used to obtain the amplitude and the propagation constant of the fundamental modes for both current and the voltage on the microstrip line. Typical numerical results are given     

Coplanar waveguide-fed circularly polarized microstrip antenna

Design of a square microstrip antenna for obtaining circular polarization (CP) radiation using a coplanar waveguide (CPW) feed is presented. This CP design is achieved by insetting a slit to the boundary of the square microstrip patch, which makes possible the splitting of the dominant resonant mode into two near-degenerate orthogonal modes for CP radiation and introducing an inclined slot in the CPW feed line for coupling the electromagnetic (EM) energy of the CPW to the square patch. Good impedance matching for CP operation can be obtained by adjusting the inclined slot length and the tuning-stub length of the CPW feed line. Typical experimental results are presented and discussed     

完全匹配层（PML）吸收边界条件的理论分析

本文以屏蔽微带线为例,应用谱域方法推导了时域差分(FDTD)法中所用的完全匹配层(PML)吸收边界条件的公式,并且严格证明了有关参数的选择原则.计算表明,在屏蔽微带线中,这种吸收边界条件的反射系数可以小于-80dB.本文所给出的推导方法对于平面分层介质结构是普遍适用的,因为谱域中的每一个波谱实际上都代表一个平面波.文中所给出的推导揭示了这种吸收边界条件的机理,它对于正确使用以及进一步改进这种吸收边界条件都是有意义的.     

ANALYSIS OF OPEN MICROSTRIP STRUCTURES BY USING DIAKOPTIC METHOD OF LINES COMBINED WITH PERIODIC BOUNDARY CONDITIONS

This paper presents the analysis of open microstrip structures by using diakoptic method of lines (ML) combined with periodic boundary conditions (PBC). The parameters of microstrip patch are obtained from patch current excited by plane wave. Impedance matrix elements are computed by using fast Fourier transform(FFT), and reduced equation is solved by using diakoptic technique. Consequently, the computing time is reduced significantly. The convergence property of simulating open structure by using PBC and the comparison of the computer time between using PBC and usual absorbing boundary condition (ABC) show the validity of the method proposed in this paper. Finally, the resonant frequency of a microstrip patch is computed. The numerical results obtained are in good agreement with those published.     

Finite element analysis of MMIC structures and electronic packagesusing absorbing boundary conditions

In this paper, a three-dimensional finite element method (FEM) is employed in conjunction with first and second-order absorbing boundary conditions (ABC's) to analyze waveguide discontinuities and to derive their scattering parameters. While the application of FEM for the analysis of MMIC structures is not new, to the best of the knowledge of the authors the technique for mesh truncation for microstrip lines using the first and higher-order ABC's, described in this paper, has not been reported elsewhere. The scattering parameters of a microstrip discontinuity are computed in two steps. As a first step, the field distribution of the fundamental mode in a uniform microstrip is obtained by exciting the uniform line with the quasi-static transverse electric field, letting it propagate, and then extracting the dominant mode pattern after the higher order modes have decayed. In step two, the discontinuity problem is solved by exciting the structure by using the fundamental mode obtained in step one. The scattering parameters based on the voltage definition are calculated by using the line integral of electric fields underneath the strip. Numerical solutions for several waveguide discontinuities and electronic packages are obtained and compared with the published data     

A spectral-domain analysis of periodically nonuniform coupledmicrostrip lines

Periodically nonuniform coupled microstrip lines are analyzed on the basis of a numerical field calculation. As the case of the single nonuniform microstrip line described in an earlier paper, Floquet's theorem is used to express all field quantities in terms of their spatial harmonics. The boundary value problem is formulated in a rigorous way and then solved using Galerkin's method in the Fourier-transform domain. Numerical and experimental results are presented     

管道焊接激光视觉跟踪的定位方法研究

为解决在管道自动焊接过程中V型坡口的识别定位问题,提出了一种基于激光视觉传感的局部区域内分步式定位方法。首先建立模板匹配,利用模板匹配方式获取焊缝初始位置区域;然后采用阈值分割和边缘提取获得激光条纹边缘线,通过Shi-Tomasi算法对边缘线进行角点检测,得到边缘线上的亚像素角点位置坐标;最后采用最小二乘法拟合得到精确的边缘直线,对上下边界线求平均值提取激光条纹的中心线,求取直线的交点得到坡口轮廓的拐点信息。通过对实际焊接现场拍摄的50幅同一高度不同位置的图像进行检测,结果表明,分步式定位方法抗干扰性强,精度较高,为完成整个跟踪自动焊接过程奠定了基础。     

Spectral-Domain Approach for Calculating the Dispersion Characteristics of Microstrip Lines (Short Papers)

The boundary value problem associated with the open microstrip line structure is formulated in terms of a rigorous, hybird-mode representation. The resulting equations are subsequently transformed, via the application of Galerkin's method in the spectral domain, to yield a characteristic equation for the dispersion properties of the open microstrip line. Numerical results are included for several different structural parameters. These are compared with other available data and with some experimental measurements.     

MoM/BI-RME analysis of boxed MMICs with arbitrarily shapedmetallizations

In this paper, we propose a novel approach for the analysis of shielded microstrip circuits, composed of a number of thin metallic areas with arbitrary shapes and finite conductivity, embedded in a multilayered lossy medium. The analysis is based on the solution of an integral equation (IE) obtained by enforcing the proper boundary condition to the electric field on the metallic areas. The IE is solved by using the method of moments with entire domain basis functions, which are numerically determined by the boundary integral-resonant-mode expansion (BI-RME) method. The use of the BI-RME method allows for the efficient calculation of the basis functions independently on the shape of the domain, thus permitting the analysis of a wide class of circuits. Two examples demonstrate the accuracy, rapidity, and flexibility of the proposed method     

Dyadic Green's functions for conductor-backed layered structuresexcited by arbitrary tridimensional sources

A general procedure for the evaluation of the dyadic Green's functions for arbitrarily oriented electric- and magnetic-current point sources embedded in a conductor-backed layered medium is presented. In the proposed approach a suitable integro-differential vectorial basis is used to split the inhomogeneous Maxwell equations, written in a transversely-invariant form, into the TE and TM wave equations. In the spectral domain (Fourier transformed domain) these equations are reduced to the usual transmission-line like equations which are solved by means of a set of auxiliary scalar Green's functions. These functions are used to express the dyadic Green's functions in the spectral as well as in the space domain. The expressions obtained contain explicit dyadic delta terms which are required to represent the electromagnetic field in the entire space including the source regions. The general theory is used to show that in the low-frequency range the electromagnetic field can be approximated by means of a TM (with respect to the interfaces normal) wave. In this manner an asymptotic form for the dynamic characteristic impedance for a microstrip line is obtained. Finally, in order to show the feasibility of the method, some comparisons with previous results concerning the electrical characteristics of a microstrip line are carried out     

新型微带缝隙天线的阻抗特性研究

在互易原理的基础上,用矩量法在谱域内求解一种新型（带盖板的）微带缝天线的输入阻抗,并与通常意义上的微带缝隙天线进行比较,开拓了微带缝隙天线的应用范围。