Satellite measurements of the HF radio environment in the topside ionosphere

Measurements made on board the orbiting Air Force meteorological satellite equipped with a high-frequency (HF) receiver have been studied in order to describe the HF radio environment at the satellite height. The satellite is in a sun-synchronous dawn-dusk orbit at a height of nearly 500 nmi (860 km) above the surface on the earth. The receiver sweeps repeatedly through the band 1.2–13.9 MHz in 10...