Measurements of beyond horizon propagation loss

The behavior of the path loss between two base stations has been investigated via measurements using one fixed transmitter and a helicopter-borne receiver. This has allowed the gathering of data for a range of distances and antenna heights, including beyond horizon conditions and antennas below and above the clutter. The data has been compared with predictions using two different path loss models that are commonly used for interference predictions. The analysis shows that these models are very useful for higher antenna heights but that they tend to over-predict the interference for lower antenna heights. Physical explanations for this difference are proposed and possible model extensions are outlined.