Transatlantic Long- Wave Radio Telephone Transmission 

 and Related Phenomena from 1923 to 1933 



By AUSTIN BAILEY and HOWARD M. THOMSON 



It is shown that transatlantic long-wave radio field strength is related to 

 the 11-year cycles of terrestrial magnetic activity, sunspots, solar limb- 

 prominences, and ultra-violet radiation. The directness of correlation 

 between long-wave radio and these other phenomena is apparently only 

 approximate. Very good seasonal and monthly correlation is obtained 

 between magnetic activity and daylight radio transmission. Magnetic 

 storms are shown to have prolonged and delayed effects on day and night 

 radio transmission, obscuring tendencies for 27-day recurrences on long 

 waves. No reference is made to the probable mechanism of long-wave radio 

 transmission because a paper, now in preparation, will be concerned pri- 

 marily with this subject. 



Introduction 



THIS paper summarizes a study of the transatlantic long- wave 

 radio transmission data (near 60 kilocycles) collected by the 

 American Telephone and Telegraph Company and the General Post 

 Office of Great Britain during the period from 1923 to 1933, including 

 the development tests from 1923 to 1926 and the period of operation 

 of the commercial radio telephone circuits from January 1927 to 

 December 1933. 



A correlation is presented between terrestrial magnetic activity, 

 sunspot-numbers, solar limb-prominences, ultra-violet radiation, and 

 transatlantic long-wave radio telephone field strength observations 

 during one 11 -year sunspot cycle. By expressing the variables with 

 different scales better correlations have been obtained. These are 

 given on averages of years, months, seasons, and days. Examples of 

 delayed night and day field strength changes accompanying long 

 magnetic storms are included in this presentation. 



It is generally believed that solar radiation influences the trans- 

 mission ^* of radio signals but the detailed mechanism by which the 

 influence is exerted ^ is not entirely clear. The number and relative 

 effects of other factors that may influence radio transmission are also 

 uncertain. Solar phenomena, magnetic activity, and radio transmission 

 appear to have some time-phase relations but these relations have not 

 been clearly established. Some of the results of the studies reported 

 herein contribute to the evaluation of these effects while other results 

 give new or corroborative information on the qualitative relations 

 between the solar, magnetic, and radio phenomena. 



* Numbers refer to the references in the bibliography. 



680 



