A new finite-difference time-domain (FDTD) algorithm for efficient field computation in resonator narrow-band structures

It is pointed out that the finite-difference time-domain (FDTD) algorithm is a versatile method capable of solving a variety of problems from circuit component characterization to radiation analyses, but it exhibits slowness in convergence when employed for the study of resonant structures, because their transient responses often exhibit a ringing behavior for a long time. Here, an approach, called the FDTD-update algorithm, that can substantially improve the convergence properties of the FDTD method when used to compute the response of resonant type structures a single frequency at a time is described. The filtering behavior of the algorithm is demonstrated by considering the problem of coupling into a cavity. Application to other problems is illustrated by solving the microstrip patch antenna configuration, for which the update algorithm is shown to enhance the accuracy of the results.>