Using Fdtd In The Microwave Circuit Applications

The finite-difference time-domain (FDTD) method is presentd by K.S.Yee in 1966, and now it is one of the most important methods in electromagnetic numerical simulations for its powerful capabilities, which has been widely used in the study of microwave circuits .The FDTD provides an effective and elegant way to solve electromagnetic distribution problems. The original FDTD divides the calculation space with a uniform grid size. Small size is good for the calculation accuracy but requires a large amount of computer memory and long calculation time. Big size is very difficult to do detailed simulation. To settle this problem some study presented non-uniform grid FDTD. Si-based microstrip circuits is analyzed by non-uniform grid FDTD.The SOC is used to remove the unwanted parasitic errors brought by the approximation of the impressed voltage sources and the feed lines. The FDTD is formulated in such a way that the port voltages and currents are explicitly represented through relevant network matrices. The application of the finite-difference time-domain(FDTD) algorithm combined with the short-open calibration (SOC) technique to three-dimensional microstrip discontinuity is presented. This new method is also used to analyze finite periodic structures. The characteristic impedance and propagation constant of local substrate integrated artificial dielectric (L-SIAD) microstricp line can be approximately obtained through analyzing only one or some cell of it. The equivalent-circuit model of its discontinuties are also analyzed by this method.