13. Ground wave propagation analysis when required

In this report the procedures for the possible way to exploit ground wave propagation have been considered. Ground wave propagation can be a reliable way to establish HF links if the frequency remains in the lower part of the range and the distance between the station points remain below 100-200 km. When the frequency and distance increase for the different reasons above explained the various mode of ground wave propagation are no more practicable. Along the LOS of 100-110 km, it results a simple and reliable way to communicate by means of the radio wave both with direct or reflected ray. Greater distances require more power in transmission and for “over the horizon” links the propagation can be done only in surface wave mode. Unfortunately the attenuation became not sustainable while the frequency or the distance increases. Even if this is a continuous process the received power dramatically decreases. In SWING context there are favorable employment conditions of the three described propagation modes.