Principles of Directive Radio Beacons utilizing Visual Reception

The need of a method of guiding sea and air craft in time of bad weather when ordinary signals are obscured has been experienced since their first use. The number of accidents at sea due to uncertainty of location in fog is certainly very great; while one of the chief deterrents to an efficient commercial air service in this country is the lack of an instrument to permit flight through fog and mist. It is related that a complete unconscious reversal in the direction of flight is not uncommon in fog.Electromagnetic waves of lengths in the radio range may be utilized for guiding purposes, as they are not appreciably absorbed by atmospheric moisture like those in the visible range. Furthermore, it has been found possible to greatly increase the usefulness of radio waves for this purpose by making them mark out in space a definite narrow zone or course which may be followed by a navigator. Not only that, but definite characteristics may be imparted to the wave, such that the navigator may determine when he is off the course, on which side, and approximately how much. Uncertainty as to position of the craft is thereby reduced to a minimum.The principles and methods of accomplishing this are set forth in this thesis, and are believed to be novel. While the work was undertaken with a view to its immediate application for aircraft, most of it can be applied without essential change to marine navigation.