Concerning the Influence of the Eleven-Year Solar Activity Period upon the Propagation of Waves in Wireless Telegraphy

Researches concerning the propagation of short and border waves, conducted by the German Air-Travel Research Laboratory during the years 1930 and 1931, reveal results which are not quite in harmony with similar, but far more complete, investigations carried out in the years 1927-28. The suspicion arises that one is here dealing with an influence exerted by the eleven-year period of solar activity upon the propagation of short and border waves, especially as such an influence upon long waves has been repeatedly established. The present work deals with the explanation of these phenomena.