Propagation Predictions for Marginal LOS Microwave Paths

This paper describes a mathematical algorithm and an associated program set developed for calculating time distributions of the effective earth-radius factor, k, for marginal line-of-sight (LOS) paths. The algorithm is a modification of a procedure developed for use in the continental United States by J. A. Schiavone at Bell Laboratories. From the distribution of k, we obtain the profile geometries applicable to various fractions of a year and from the geometries, median basic transmission loss values and antenna pointing losses are calculated. The method is useful because military LOS paths are often long and are designed with limited terminal site options. Schiavone´s model depends upon values for a number of climatological parameters. This paper lists sources and describes methods for estimating these values and provides an alternative method for mathematically expressing the refractivity distribution.