Radio wave propagation along mixed paths in forest environments

The propagation of radio waves is examined for communication paths that may be partly within a forest and partly in regions outside the vegetation. Analytic results are found for simple canonic geometries in which the fields can be described in terms of ray-trajectories. By viewing a realistic forest environment as a combination of such canonic cases, it is possible to evaluate radio losses in complex situations by using a ray-tracking approach. The pertinent fields can then be expressed in terms of relatively simple analytical expressions, which hold well for frequencies between 2 and 200 MHz.