L- and C-band airframe shadowing measurements and statistics for a medium-sized aircraft

Airspaces worldwide are becoming more heavily used. This includes the use of unmanned aircraft systems, which is rapidly growing. In order to ensure reliable communication for aircraft, the air-ground channel must be accurately characterized. A significant channel impairment that has not been thoroughly studied is airframe shadowing-obstruction of the line-of-sight signal by the aircraft itself. In this paper, we report on measured results for this shadowing phenomenon in two frequency bands, for a medium-sized aircraft. We present results for two example shadowing events in terms of shadowing depth and duration, and provide distributions of shadowing depth and duration for our entire data set. We show that for both bands, airframe shadowing can be more than 30 dB, and can last for tens of seconds.