Terrestrial Magnetism and Its Relation to World-Wide Short-Wave Communications

The functioning of short-wave circuits is found to be closely related to the geographical distribution of terrestrial magnetic activity. Circuit fading and magnetic fluctuations may be correlated in terms of horizontal intensity communication limits. North American magnetogram studies have provided a direct relationship between short-wave communication effectiveness and north latitude. The world may be allocated into zones of commercially effective, disturbed, and dead sectors with respect to any communication center. The relative performance of east-west versus west-east transatlantic communication, and the application of magnetic analysis to international broadcasting is considered. The magnetic history of the year 1932 with respect to mean intensity and range shows the core of the earth to have magnetic retentivity. The correspondence of magnetic, earth current, and signal variations is illustrated. Europe is shown to be more favorably located geographically and diurnally with respect to freedom from terrestrial disturbances to communications than is North America. A knowledge of concurrent magnetic activity, and the systematic charting of its cycles of daily variations is found essential to the most effective use of facilities, at all times and seasons, in the maintenance of a world-wide radio communications service.