Finite difference time domain analysis of circular microstrip antennas

The finite difference time domain (FDTD) method has been applied with considerable success to the analysis of impedance characteristics of rectangular microstrip antennas. Conspicuously absent from the literature, however, are applications of the FDTD method to an important class of microstrip radiators that use circular or elliptical patch elements. This contribution describes the application of the FDTD method to the analysis of the impedance characteristics of a circular patch microstrip antenna fed directly by a microstrip transmission line. A cartesian grid is used to model the majority of the computational domain with locally distorted cells in the vicinity of the patch perimeter that conform to the curved conductor edge. The contour path method is used to update the field components associated with the distorted cells.