Finite-difference Time-domain Method Algorithm Research Articles

Analysis of GPR Wave Propagation in Complex Underground Structures Using CUDA-Implemented Conformal FDTD Method

Ground penetrating radar (GPR), as a kind of fast, effective, and nondestructive tool, has been widely applied to nondestructive testing of road quality. The finite-difference time-domain method (FDTD) is the common numerical method studying the GPR wave propagation law in layered structure. However, the numerical accuracy and computational efficiency are not high because of the Courant-Friedrichs-Lewy (CFL) stability condition. In order to improve the accuracy and efficiency of FDTD simulation model, a parallel conformal FDTD algorithm based on graphics processor unit (GPU) acceleration technology and surface conformal technique was developed. The numerical simulation results showed that CUDA-implemented conformal FDTD method could greatly reduce computational time and the pseudo-waves generated by the ladder approximation. And the efficiency and accuracy of the proposed method are higher than the traditional FDTD method in simulating GPR wave propagation in two-dimensional (2D) complex underground structures.

Modeling and Analysis of Conducted and Radiated Emissions Due to Common Mode Current of a Buck Converter

This paper presents the study of conducted and radiated emissions due to common-mode (CM) currents flowing through the power cables of a DC–DC converter system. In order to predict the conducted electromagnetic interferences (EMI) emissions, a model of power converter system is presented. The finite-difference time-domain method (FDTD) is used for predicting the magnetic near field radiated by the power supply cable of a buck converter and that due to CM current flowing through the cable. The CM current resulting from the model is compared with the experimental ones and implemented in the FDTD algorithm as current source of disturbance. The comparison with experimental results shows the validity of the FDTD model over a wide frequency range. The goal of this study is to predict the level of conducted and radiated EMI emissions. Therefore, proposing and investigating a simple and effective filtering solution that allows to reduce the emissions located in the switching noise zone, the results show that the conducted and radiated emission levels can be reduced by as much as 30 dB when using this technique.

A Parallel Graded-Mesh FDTD Algorithm for Human–Antenna Interaction Problems

The finite difference time domain method (FDTD) is frequently used for the numerical solution of a wide variety of electromagnetic (EM) problems and, among them, those concerning human exposure to EM fields. In many practical cases related to the assessment of occupational EM exposure, large simulation domains are modeled and high space resolution adopted, so that strong memory and central processing unit power requirements have to be satisfied. To better afford the computational effort, the use of parallel computing is a winning approach; alternatively, subgridding techniques are often implemented. However, the simultaneous use of subgridding schemes and parallel algorithms is very new. In this paper, an easy-to-implement and highly-efficient parallel graded-mesh (GM) FDTD scheme is proposed and applied to human–antenna interaction problems, demonstrating its appropriateness in dealing with complex occupational tasks and showing its capability to guarantee the advantages of a traditional subgridding technique without affecting the parallel FDTD performance.

Some considerations for using the finite difference time domain technique to analyze microwave integrated circuits

The authors describe the incorporation of the autoregressive method (AR model) and Litva's dispersive boundary condition (DBC) into the finite-difference time-domain method (FD-TD). It is found that the performance of the FD-TD technique is greatly enhanced when used to simulate microwave passive circuits. The results of this study show that for the analysis of typical high-Q circuits, CPU-time savings of up to 90% can be realized by combining AR model and FD-TD. After testing a number of different 50-ohm microstrip lines, the authors conclude that DBC shows good performance and gives excellent results when implemented with FD-TD, if the parameters are chosen properly. The use of this boundary condition can result in a considerable improvement in the accuracy of FD-TD simulations. These results help to demonstrate the usefulness of incorporating both the DBC and AR model with the FD-TD algorithm when analyzing practical microwave circuits. >