Comparison of GTD and FDTD predictions for UHF radio wave propagation in a simple outdoor urban environment

The continuing growth of wireless communication systems has led to an interest in the development of site-specific propagation models. In designing microcell systems there is a often a desire to have a good understanding of the propagation characteristics within the cell. Site-specific models offer a fast and inexpensive means of obtaining this information without the need for on-site measurements. The finite difference time domain (FDTD) method was initially developed by Yee in 1966. The method is commonly applied to three-dimensional scattering and radiation problems. But with the exception of analyzing the propagation within a single room, even the largest computers do not have nearly enough memory to model full three-dimensional indoor or outdoor propagation problems. However, in many cases a two-dimensional approximation to the geometry can be used, and two-dimensional FDTD has previously been applied to indoor propagation. This paper considers the application of 2D FDTD to a simple outdoor environment and develops a simple approach for introducing the correct spherical wave spreading. Comparisons to FDTD predictions could be used to evaluate and refine the GTD based methods.