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An unconditionally stable Crank–Nicolson finite-difference time-domain (CN-FDTD) algorithm is presented for three-dimensional microwave circuit analysis. First, Mur's first–order absorbing boundary condition is applied this CN-FDTD algorithm. A symmetric successive over relaxation–preconditioned biconjugate-gradient algorithm is also proposed to solve the large sparse matrix equation obtained in the CN-FDTD method. Resonant cavity and several planar microstrip circuits are presented to illustrate the versatility of this technique. Numerical results indicate that with a time-step size excessively larger than the Courant–Friedrich–Levy limit, the accuracy of CN-FDTD is still much higher than that of the alternating-direction implicit FDTD. [ABSTRACT FROM AUTHOR]

A novel numerical de-embedding scheme called the short-open calibration (SOC) technique, in conjunction with the vector finite element method (FEM), has been developed to characterize two-port network of arbitrarily shaped, three-dimensional discontinuities in microwave circuits. This SOC technique is effectively implemented into the FEM for boundary truncation of the unbounded circuit structures. In such a manner, fast convergence of iterative solver for large-sparse linear matrix equations from FEM is achieved. The SOC technique is used to remove parasitic effects brought by the approximation of the impressed voltage source and also the problem of resulting consistency between the two- and three-dimensional simulations. Scattering parameters of discontinuous sections are constructed from the definition of port voltages and currents. Numerical solutions are well compared with those published in the available literatures. It is demonstrated that the features of the SOC technique are advantageous when combined with FEM for electromagnetic problems. Copyright © 2002 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The multifrontal method is applied for solving a large, sparse, and unsymmetric system of linear equations resulting from the use of the edge-based finite-element method (FEM). The finite-element method combined with perfectly matched layers (PML) is given for simulation of microwave devices, and the combined algorithm of the multifrontal method is described. The electrical characteristics of typical waveguide devices such as the ferrite phase shifter and circulator are analyzed, and the calculated results are compared with those obtained from the literature. In order to demonstrate the efficiency of the multifrontal method, the computational time is compared with that of both successive overrelaxation (SOR) preconditioned conjugate-gradient (PCG) and conjugate-gradient methods (CG) for the phase shifter. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 76–81, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10521 [ABSTRACT FROM AUTHOR]

The multifrontal method is applied for solving a large system of linear equations resulting from the use of the edge-based finite-element method (FEM). The finite-element method combined with the perfectly matched layers (PMLs) is given for the simulation of microwave filters, and the algorithm of the multifrontal method is described in detail. The reflection loss and insertion loss of several filters are analyzed as examples, and the obtained results are compared with those obtained from the literature. In order to demonstrate the efficiency of the multifrontal method, the computational time is compared with that of both the symmetric successive overrelaxation (SSOR) preconditioned conjugate-gradient (PCG) and conjugate-gradient methods (CG) for a thick-iris waveguide bandpass filer. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 465–470, 2001. [ABSTRACT FROM AUTHOR]

In this paper, the application of the edge-based vector finite-element method combined with the short-open calibration (SOC) technique to three-dimensional waveguide discontinuity was presented. This SOC technique is directly accommodated in the FEM algorithm, and is used to truncate the computational domain. The developed FEM algorithm is applied to the modeling of dielectric-filled waveguide discontinuities that can be segmented into two distinct sections: the static model of feed lines, and the dynamic model of circuit discontinuity. The FEM is formulated in such a way that the port voltages and currents are explicitly represented through relevant network matrices. The SOC technique is used to remove or separate unwanted parasitics brought by the approximation of the impressed voltage source, as well as the problem of the resulting consistency between different simulations. Truncation of the computational domain by the SOC technique makes the iterative solvers for large sparse linear matrix equations from the FEM converge much faster than by perfectly matched layers (PML). Results for full-height/partially dielectric-filled waveguide discontinuities are very well compared with available publications. © 2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 27: 438–444, 2000. [ABSTRACT FROM AUTHOR]