Spherical propagation models for multipath-propagation predictions

Multipath fading leads to a limitation in the availability and/or reliability of microwave links. To study the propagation mechanism under fading conditions propagation models, based on ray theory, above a spherical earth were developed and compared to the well-known planar propagation model above a flattened earth. The reasons for studying spherical propagation models are: (1) to avoid the limitation of small elevation angles in planar propagation models, (2) to investigate the computed and measured path delay on the microwave line of sight links, and (3) to set up an analytical approach for the spherical propagation model without numerical difficulties and computing-time intensive procedures. Computational results of the models are shown, including and accuracy analysis, and the use of spherical propagation models is illustrated for surface duct layers above water.