Physical Aspects of Radio Telegraphy

The development of radio telegraphy, as a mysterious and little understood physical art, from well known inductive and conductive methods of telegraphy is briefly stated. It is shown that radio telegraphy is now subject to engineering treatment and consists of a series of expected effects resulting from a series of controllable causes. The large scope of natural phenomena involved is outlined, and the general physical basis of all communication systems stated. The fundamental operation of transmitters and receivers, from those first used to the most modern sustained-wave-heterodyne apparatus, is described. Difficulties produced by atmospheric disturbances, and their effects upon the requirements of commercial radio telegraphy are discussed. Following the qualitative considerations, some of the quantitative physical relations involved in practical radio telegraphy are outlined. Important constants for transmission over distances of 2,000, 3,000, 4,000, and 5,000 kilometers are given, and the paper concludes with a brief outline of future development.