A Radio Range Beacon Free from Night Effects

A radio range beacon, suitable for the guidance of aircraft along established airways, which is entirely free from atmospheric variations or "night effects", is described. Advantage is taken of the phenomenon that waves of frequencies higher than 30 megacycles per second, or thereabouts, are not usually refracted back to the earth by the Kennelly-Heaviside layer. Multiple path transmission, variation in signal intensity and in polarization are thus avoided. A four-course aural beacon operating on 34.6 megacycles per second was employed for the experimental work. Results and applications are discussed.