It used to be that a wing wave or rapid tail deflection was all that was needed by the pilot of an aircraft to acknowledge a visual queue from a person on the ground. The evolution of electronic ...

Abstract: High Frequency (HF) communication systems use radio waves at frequencies in the range of 3-30 MHz propagating in the form of skywave with the help of the ionosphere. For emergency ...

Abstract: The multi-frequency multipath observations of temporal variations in the Doppler spectra and signal amplitudes of HF radio waves reflected from the ionosphere, which accompanied ionospheric ...