A three‐dimensional mesh refinement algorithm with low boundary reflections for the finite‐difference time‐domain simulation of metallic structures

We present a method for including areas of high grid density into a general grid for the finite‐difference time‐domain method in three dimensions. Reflections occurring at the boundaries separating domains of different grid size are reduced significantly by introducing appropriate interpolation methods for missing boundary points. Several levels of refinement can be included into one calculation using a hierarchical refinement architecture. The algorithm is implemented with an auxiliary differential equation technique that allows for the simulation of metallic structures. We illustrate the performance of the algorithm through the simulation of metal nano‐particles included in a coarser grid and by investigating gold optical antennas. Copyright © 2009 John Wiley & Sons, Ltd.     

Transient analysis of printed lines using finite‐difference time‐domain method

Comprehensive studies of ultra‐wideband pulses and electromagnetic coupling on printed coupled lines have been performed using full‐wave 3D finite‐difference time‐domain analysis. Effects of unequal phase velocities of coupled modes, coupling between line traces, and the frequency dispersion on the waveform fidelity and crosstalk have been investigated in detail. To discriminate the contributions of different mechanisms into pulse evolution, single and coupled microstrip lines without (ϵ_r = 1) and with (ϵ_r > 1) dielectric substrates have been examined. To consistently compare the performance of the coupled lines with substrates of different permittivities and transients of different characteristic times, a generic metric similar to the electrical wavelength has been introduced. The features of pulse propagation on coupled lines with layered and pedestal substrates and on the irregular traces have been explored. Physical interpretations of the simulation results are discussed in the paper. Copyright © 2012 John Wiley & Sons, Ltd.     

Global modeling of nonlinear circuits using the finite‐difference Laguerre time‐domain/alternative direction implicit finite‐difference time‐domain method with stability investigation

This paper describes a new unconditionally stable numerical method for the full‐wave physical modeling of semiconductor devices by a combination of the finite‐difference Laguerre time‐domain (FDLTD) and alternative direction implicit finite‐difference time‐domain (ADI‐FDTD) approaches. The unconditionally stable method by using FDLTD scheme for the electromagnetic model and semi‐implicit ADI‐FDTD approach for the active model leads to a significant decrease in the full‐wave simulation time. Numerical simulations of an example transistor and a power amplifier show the efficiency of presented method for the full‐wave simulation of mm‐wave active circuits. Copyright © 2012 John Wiley & Sons, Ltd.     

Finite‐difference time‐domain analysis of radiation characteristics of monopoles on space probes

A general numerical solution based on finite‐difference time‐domain (FDTD) is presented to calculate the radiation characteristics of wire antennas on space probes. The method is versatile and can treat conductor loss, arbitrary‐shaped probes, and wires as well as inhomogenities. Numerical results are obtained and compared with those for a few specific cases available in the literature. Additionally, laboratory models of the antennas have been built and their properties have been measured for comparison with computed results. Copyright © 2008 John Wiley & Sons, Ltd.     

An overlapping Yee finite‐difference time‐domain method for material interfaces between anisotropic dielectrics and general dispersive or perfect electric conductor media

A novel stable anisotropic finite‐difference time‐domain (FDTD) algorithm based on the overlapping cells is developed for solving Maxwell's equations of electrodynamics in anisotropic media with interfaces between different types of materials, such as the interface between anisotropic dielectrics and dispersive medium or perfect electric conductor (PEC). The previous proposed conventional anisotropic FDTD methods suffer from the late‐time instability due to the extrapolation of the field components near the material interface. The proposed anisotropic overlapping Yee FDTD method is stable, as it relies on the overlapping cells to provide the collocated field values without any interpolation or extrapolation. Our method has been applied to simulate electromagnetic invisibility cloaking devices with both anisotropic dielectrics and PEC included in the computational domain. Numerical results and eigenvalue analysis confirm that the conventional anisotropic FDTD method is weakly unstable, whereas our method is stable. Copyright © 2013 John Wiley & Sons, Ltd.