Zhi-Qiang Bi

A dispersive boundary condition for microstrip component analysis using the FD-TD method

A dispersive absorbing boundary condition (DBC) which allows the dispersion characteristics of waves to be used as a criterion for designing absorbing boundary conditions is presented. Its absorbing quality is superior to that of the presently used Murs first-order boundary condition for microstrip component analysis, and its implementation is much simpler when compared to that of the super boundary condition treatment. Due to the significant performance improvement of the new boundary condition, the memory requirement can be reduced greatly when applying this boundary condition to microstrip component analysis. >

Accurate characterization of planar printed antennas using finite-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. >

Fast finite-difference time-domain analysis of resonators using digital filtering and spectrum estimation techniques

The use of digital filtering and spectrum estimation techniques for improving the efficiency of the FD-TD algorithm in solving eigenvalue problems is discussed. The great improvement of the efficiency of the method is demonstrated by means of both numerical and measurement results. In addition, several improvements to the present FD-TD method for eigenvalue analysis are presented. These include the analysis of open dielectric resonators and the extraction of the resonant frequencies from the FD-TD results. The result for the open dielectric resonator analysis is validated using measured data. >

A new finite-difference time-domain algorithm for solving Maxwell's equations

An algorithm is presented for deriving finite-difference-time-domain (FD-TD) solutions of Maxwells equations. When compared with Yees method (1966), it is found that the stability conditions for this method exceed those of Yees method by the factors 1.41 and 1.73, respectively, for the two-dimensional and three-dimensional cases. The algorithm is compatible with both Yees method and the finite-element-time domain method, thereby allowing for unification of the two. The algorithm will also provide greater flexibility in formulating and studying the multigrid method, the variable mesh method, and the method of finite difference approximations of the boundary conditions.<<ETX>>

Enhancing finite-difference time-domain analysis of dielectric resonators using spectrum estimation techniques

The authors discuss the use of digital filtering and spectrum estimation techniques for improving the efficiency of the finite-difference-time-domain (FD-TD) algorithm for solving eigenvalue problems. It is demonstrated by means of numerical results that the efficiency of the FD-TD method for dielectric resonator analysis has been improved by at least one order of magnitude, without any loss of accuracy in calculating the resonant frequencies. This new result makes it possible to use the FD-TD method as a practical design tool for dielectric resonator analysis.<<ETX>>

Full-wave analysis of an assortment of printed antenna structures using the FD-TD method

Simple and complex microstrip antennas are analyzed using the FDTD (finite-difference-time-domain) method. The complex antennas that are analyzed consist of broadband and/or dual-band aperture-coupled stacked microstrip antennas. The strengths and the limitations of the FDTD technique for microstrip antenna analysis are demonstrated by comparing the FDTD results with experimental results. It is also shown that the FDTD method is a very useful tool for designing wideband and multiple-band microstrip antennas.<<ETX>>

Boundary conditions for the FD-TLM method

The first order absorbing boundary condition for the FD-TLM (finite-difference transmission line matrix) method and the dispersive boundary condition for the FD-TLM method have been developed. Both the validity and the efficiency of the two kinds of boundary conditions have been demonstrated by means of analysis of microstrip transmission line.<<ETX>>

FD-TD analysis of waveguide components using dispersive boundary conditions (DBC)

The dispersive absorbing boundary condition (DBC) developed in [1] for microstrip component analysis, a case where dispersion is week, is now applied to a strongly dispersive case which occurs in conductor waveguides. The absorbing quality of the DBC is found to be much superior to that of the absorbing boundary conditions that are currently used for waveguide component analysis. Due to the significant performance improvement and the easy implementation of the DBC, the accuracy and the efficiency can be improved greatly when applying the boundary condition to waveguide component analysis.

Efficient FD-TD analysis of dielectric resonators with tuning screw and multilayer structure

An efficient finite difference time domain method, coupled with digital filtering and spectrum estimation techniques, was used to analyze the resonant frequencies and field distribution of two resonant structures of practical importance. The semiconductor-dielectric multilayer resonators, which are important in optically controlled circuits, were analyzed, and found to be in reasonable agreement with the experimental results. The results of a practical tuning screw dielectric resonator are also given and compared with the available rigorous results.<<ETX>>