  This paper studies the air-to-ground (AG) ultra-wideband (UWB) propagation
channel through measurements between 3.1 GHz to 4.8 GHz using
unmanned-aerial-vehicles (UAVs). Different line-of-sight (LOS) and obstructed-
LOS scenarios and two antenna orientations were used in the experiments.
Channel statistics for different propagation scenarios were obtained, and the
Saleh-Valenzuela (SV) model was found to provide a good fit for the statistical
channel model. An analytical path loss model based on antenna gains in the
elevation plane is provided for unobstructed UAV hovering and moving (in a
circular path) propagation scenarios.
