Application of the Z-transform technique for modeling lumped load in the FDTD

In this paper, we present a Z-transform technique to derive an updating algorithm for the finite difference time domain (FDTD) technique dealing with a lumped load. Such a load can be used to simulate equivalent circuits of some parts of microstrip structures, far field pattern calculation of a patch antenna fed by infinite feed lines, backing with including integrated circuits or digital devices. To validate the technique, we investigate the problem of a lumped circuit termination of a uniform microwave stripline.