Application Research Of FDTD In Microstrip Circuits

This paper studied the application of finite difference time domain method (FDTD) in microstrip circuits. Signal transmission in different microstrip lines has been studied mainly. At the same time two methods based on FDTD for microstrip circuits with lumped elements have been discussed briefly and used for analyzing several practical circuits.First of all, the basic principle of finite difference time domain method that was composed of difference equations, stability condition, numerical dispersion characteristics and absorbing boundary conditions was introduced as well as the imported excitation in three-dimensional space.In addition, the signal transmission in different microstrip lines, such as uniform microstrip line, ladder microstrip line and corner microstrip line, was measured by distortion coefficient a new concept in the paper.Finally, two effective FDTD methods for microstrip circuits with lumped elements were presented. One was extended FDTD including the equivalent current source method and the equivalent voltage source method. The equivalent methods for different sizes elements were discussed based on the extended FDTD. The other was the combination of FDTD with SPICE. FDTD-SPICE was used to analyze the high-speed signal transmission in the microstrip circuits of PCB board which were analyzed briefly. The effectiveness of the algorithms was demonstrated through several practical examples, the results of which could provide references to engineering design.