An Empirical Propagation Model (EPM-73)

A propagation model is described which has the advantage of simplicity of manual calculations of basic transmission loss (Lb), and which provides a degree of accuracy which is similar to that obtained with other more sophisticated models which compute Lb. The model uses a minimum number of parameters and is based on both theoretical and empirical considerations. Also, inverse solutions may be obtained. That is, given a value of Lb and, for example, antenna heights and frequency, the appropriate value of distance may be calculated. The model provides an estimate of mean basic transmission loss. in dB, with an associated standard deviation. It has been compared with measured values over a frequency range of approximately 20-10 000 MHz. Approximately 7 000 paths have been considered in many different areas. Comparison with other more sophisticated models indicates comparable results, including predictions for sea water paths and for frequencies down to 1 MHz (but not substantiated by measurements between 1 and 20 MHz).