Numerical analysis of arbitrarily shaped discontinuities betweenplanar dielectric waveguides with different thicknesses

An approach that combines the finite-element and boundary-element methods is applied to the analysis of arbitrarily shaped discontinuities between planar dielectric waveguides with different thicknesses. The fields interior and exterior to the region enclosing the discontinuities are treated by the finite-element method and the boundary-element method, respectively. The waveguide regions connected to the discontinuities are handled by analytical solutions. In this approach, scattering characteristics of the discontinuities can be accurately evaluated, and far-field radiation patterns can be easily calculated. To show the validity and usefulness of this approach, the scattering characteristics of a step, a staircase transformer, and a tapered transformer are analyzed. Also, a simple equivalent network approach is introduced for estimating the reflection and transmission characteristics of planar dielectric waveguide discontinuities, and the effectiveness of this simple approach is confirmed by comparing the numerical results with those of the approach that combines the finite-element and boundary-element methods     

Efficient modal analysis of arbitrarily shaped waveguides composed of linear, circular, and elliptical arcs using the BI-RME method

This paper deals with the accurate and efficient modal analysis of arbitrarily shaped waveguides whose cross section is defined by a combination of straight, circular, and/or elliptical arcs. A novel technique for considering the presence of circular and/or elliptical segments within the frame of the well-known boundary integral-resonant mode expansion (BI-RME) method is proposed. This new extended BI-RME method will allow a more accurate solution of a wider number of hollow conducting waveguides with arbitrary profiles, which are usually present in most modern passive waveguide components. To show the advantages of this new extended technique, the modal chart of canonical (circular and elliptical) waveguides, as well as of irises with great practical interest (i.e., cross-shaped irises with rounded corners) has been first successfully solved. Next, a computer-aided-design software package based on such a novel modal analysis tool has first been validated with the accurate analysis of a referenced complex dual-mode filter, and then applied to the complete design of a novel twist component for K-band application based on circular and elliptical waveguides. A prototype of this novel device has been manufactured and measured for verification purposes.     

Computer analysis method for arbitrarily shaped microstrip antenna with multiterminals

An analysis method is presented for an arbitrarily shaped microstrip antenna with multiterminals. The method is based on the variational method and the modal-expansion technique. Eigenvalues and eigenfunctions are determined using the Rayleigh-Ritz method. Input impedance and other antenna parameters are derived at nonresonance. Furthermore, the network model, useful for the network analysis of a microstrip antenna with multiterminals, is presented by introducing an ideal transformer. Finally, numerical examples are compared with experimental results. The agreement is quite good, and the validity of the present method is confirmed.     

A full-wave modal analysis of arbitrarily shaped waveguidediscontinuities using the finite plane-wave series expansion

A full-wave electromagnetic model for analyzing waveguide discontinuities of arbitrarily shaped piecewise planar boundaries is presented. The analysis is facilitated by using the finite plane-wave series expansion of circular cylindrical modal functions. Since electromagnetic fields on each of the planar boundary surfaces of the inhomogeneous region are expressed in terms of plane-wave modal functions, the complete solution is carried out analytically without any numerical integration. To verify the formulation, a number of practical waveguide components are analyzed. The calculated results are compared with other full-wave electromagnetic models. Excellent agreement is obtained for all the cases     

Static analysis of arbitrarily shaped conducting and dielectricstructures

In this paper, a simple and efficient numerical procedure is presented to compute the charge distribution and capacitance of conducting bodies in the presence of dielectric structures of arbitrary shape and finite size. The method presented is robust and provides accurate results for both low as well as high dielectric-constant materials as supported by numerical examples     

Finite-element solution of planar arbitrarily anisotropic diffused optical waveguides

The finite-element method for propagation in planar anisotropic diffused optical waveguides with arbitrary permittivity tensor is presented. A Galerkin procedure has been introduced to the finite-element formulation, to study both the nonleaky and leaky surface waves. The complex propagation constants are determined as a function of frequency for possible modes of propagation. The accuracy of the method has been checked by calculating the nonleaky and leaky surface waves of Ti-diffused LiNbO3waveguides with Gaussian index profiles. The numerical results of Ti-diffused LiNbO3waveguides with dielectric overlays are also presented and the effects of dielectric overlays on the propagation characteristics for the nonleaky and leaky surface waves are examined.     

Computer-aided analysis of arbitrarily shaped, coaxialdiscontinuities

The author proposes a method of analyzing a coaxial discontinuity arbitrarily shaped in two dimensions (radial and longitudinal) but maintaining its axial symmetry. It is shown that under such assumptions the equations to be solved correspond to the equations describing an equivalent planar circuit filled with a nonuniform medium. These equations are solved by a version of the finite-difference time-domain method. The method produces a universal computer algorithm capable of solving a wide range of practical problems with no analytical preprocessing. The examples presented show that the method can be effectively used in engineering applications     

任意形状天线罩的快速分析

将自适应积分算法与体积分方程相结合分析任意形状天线罩对天线辐射特性的影响。将任意形状的天线罩剖分成四面体，基于体积分方程的自适应积分快速算法求出天线罩上的感应电流，即可求出天线-天线罩系统的总场。自适应积分快速算法的应用提高了矩量法的计算速度，并大大缩减了需要的存储量，从而使该方法可用于分析电尺寸较大的天线罩.最后,分别计算了球形、锥形天线罩存在时理想电振子阵列的辐射方向图。     

Generalized fourier series expansion method for determining cutoffs in optical waveguides

In weakly guiding analysis of cutoff frequencies in general optical waveguides, the proposed generalized Fourier series expansion method in elliptical coordinates has advantages in terms of generality, accuracy, efficiency and simplicity. Numerical data of higher mode cutoffs in elliptical and rectangular optical waveguides show the excellent agreement between the present method and the finite element method.     

Modal analysis of strip-loaded diffused optical waveguides by a variational method

The propagating modes supported by strip-loaded three-dimensional diffused optical waveguides are analyzed in detail theoretically by using a variational method. Some typical numerical examples of the propagation constants and the field distributions are illustrated. The dependence of propagation characteristics on the geometrical parameters of the loading dielectric strip is discussed.     

Bistatic scattering by arbitrarily shaped objects with rough surface at optical and infrared frequencies

The scattering cross sections for arbitrarily shaped dielectric objects with rough surface are determined for optical and infrared frequencies using the Kirchhoff approximation. The formula of the coherent scattering cross section is derived, and numerical method of incoherent scattering cross section is given. As a specific example, the infrared laser scattering cross sections of rough spheres are calculated at 1.06 μm.     

Elliptical Fourier series expansion method together with cutofffrequencies in elliptical optical waveguides

In the weakly guiding analysis of cutoff frequencies in elliptical optical waveguides, the advantages of the proposed elliptical Fourier series expansion method in generality, accuracy, efficiency and simplicity are demonstrated through detailed comparisons with the precise Mathieu function method, the finite element method, Dyott's measurements on practical fibers and many other important techniques. Several issues in debate for long on the subject could be resolved     

A general power-series expansion method for exact analysis of the guided modes in an optical fiber

A power-series expansion method for rigorous analysis of the guided modes in a cylindrical, radially inhomogeneous, dielectric waveguide is presented. The method is developed for an arbitrary piece-wise polynomial permittivity profile. The field solutions of the inhomogeneous core are constructed by a sequence of power-series expansions. Convergence is ensured and accuracy maintained by regulating the distance between successive expansion points. The characteristic equation and the cutoff conditions are expressed in a unified manner as a set of functions. The method presented is competitive in terms of accuracy achieved and computing time required.     

An economic method for the solution of the scalar wave equation forarbitrary shaped optical waveguides

The discrete sine method, in which the basis functions consist of sine functions defined on a set of parallel discretization lines, is discussed. The method is a combination of a scalar version of the finite difference method and sine method. The choice of the basis set leads for the eigenvalue equation to be solved, to a sparse matrix with a small bandwidth. As a consequence, the propagation constant of guided modes in optical waveguides may be calculated with short computation times and low storage needs. Results obtained with the method for three different wave guiding structures are compared with those of other methods     

Numerical analysis of arbitrarily shaped probe-excited single-armprinted wire antennas

A general integral equation technique is described for analysis of an arbitrarily shaped single-arm printed wire antenna excited through a vertical probe. A unified current integral equation is formulated on the basis of dyadic Green's functions and the reciprocity theorem. The current distribution is obtained by using a parametric moment method in which parameter segments are adopted for the printed wire instead of the commonly employed wire length segments. The radiation field solution involving both the printed antenna and vertical probe is also presented. The validity of the formulation is verified by comparing the numerically obtained input impedance and radiation patterns for a linear antenna and a meander antenna with measured data. A circular open loop and an Archimedian spiral are investigated to illustrate the applicability of the present technique     

Computer-aided analysis of a finite arbitrarily shaped dielectric antenna

A numerical method of analysis is developed to determine the characteristics of a homogeneous dielectric antenna of arbitrary shape based on a general expression of electromagnetic wave scattering by a homogeneous dielectric body derived by Barrar and Dolph. This method is tested on a dielectric-disk antenna.     

Accurate analysis of arbitrarily shaped patch resonators on thinsubstrates

Based on a generalized edge boundary condition (GEBC), an accurate analysis method for arbitrarily shaped microstrip patch resonators is developed. The edge of the patch and its feeding line are first discretized as a series of connected segments. Next, an equivalent voltage and an equivalent current are defined on each segment. This boundary of the patch and the feeding line can be viewed as an interface between two networks. The first takes into account the coupling under the patch. The second represents the dynamical edge effects and the coupling over the top side of the patch. This general and computer-efficient approach is then successfully applied to determine the input impedance of some commonly used probe-fed and strip-fed patch resonators     

Analysis of arbitrarily shaped two-dimensional microwave circuitsby finite-difference time-domain method

A version of the finite-difference time-domain method adapted to the needs of S-matrix calculations of microwave two-dimensional circuits is presented. The analysis is conducted by simulating the wave propagation in the circuit terminated by matched loads and excited by a matched pulse source. Various aspects of the method's accuracy are investigated. Practical computer implementation of the method is discussed, and an example of its application to an arbitrarily shaped microstrip circuit is presented. It is shown that the method in the proposed form is an effective tool of circuit analysis in engineering applications. The method is compared to two other methods used for a similar purpose, namely the contour integral method and the transmission-line matrix method     

Analysis of arbitrarily shaped multiple-dielectric posts in rectangular waveguide by method of lines

The equivalent network of arbitrarily shaped multiple-dielectric posts in a rectangular waveguide is analysed by the method of lines and the equivalent parameters of three cylindrical dielectric posts in a rectangular waveguide are calculated as an example.<>