Propagation measurements on a line-of-sight over-water radio link in Norway

Propagation measurements have been carried out on a 43 km long 13 GHz 128 QAM (quadrature amplitude modulation) over-water path in the coastal regions of Norway. The measurements lasted for 18 months. The intention with the measurements on this in-service radio link was to compare results with models given by the (Recommendation International Telecommunication Union) Rec. ITU-R P. 530–15. The attenuation due to combined rain and wet snow was of special interest, since the radio link is situated in an area — Trondheimsfjorden — that has a significant amount of wet snow in winter. The radio link experienced outages due to multipath, rain and wet snow, where the latter were the predominant outage cause. The fading due to combined rain and wet snow resembled the shape of the model given in Rec. ITU-R P. 530–15, but the model underpredicts the amount of fading. In addition to outages (performance degradation and unavailability) and fading, various other parameters such as fading speed, enhancement, average fade duration, and number of fade events have been measured and compared to Rec. ITU-R P. 530–15. The radio link activity has also been compared to the weather conditions at the time for the most severe fading incidents.