314 BELL SYSTEM TECHNICAL JOURNAL 



reasonably suitable terrain for receiving antenna construction, and 

 adequate wire connection facilities between the location and the more 

 densely populated areas. 



Since about 10 per cent of the populations of the United States and 

 the British Isles are located within a radius of 40 miles of New York 

 and London, respectively,'^ it was natural to decide upon making those 

 cities the terminal points. It would hence be desirable to locate the 

 receiving stations near and with good wire circuits to those cities. 



Very early in the history of radio communication ^ it was, however, 

 realized that in the United States a decrease of radio noise was obtained 

 by a northerly location of the receiving station and, for receiving from 

 European stations, the northern location is further advantageous, since 

 higher field strengths result from the reduced transmission distance. 

 The Radio Corporation of America had already taken advantage of 

 this improvement by locating a receiving station at Belfast, Maine. 



To obtain quantitative information on this matter, the American 

 Telephone and Telegraph Company made comparative measurements 

 of noise as received on loop antennas at Riverhead, New York; Green 

 Harbor, Massachusetts; and Belfast, Maine; the loops were so oriented 

 as to give maximum receptivity in the direction of England. Although 

 these tests were only continued for a few months at each location, they 

 left no doubt that the absolute level of the noise was less at the 

 northerly locations. 



In Fig. 3, there is shown the diurnal variation of improvement in 

 noise conditions (in TU) for average days of each month at Belfast 

 over Riverhead. The average hourly improvement was determined 

 by averaging the ratios of practically simultaneous observations of 

 noise at the two locations for each hour during any one month and 

 taking a three-hour moving average of the result to reduce the effect 

 of purely local phenomena at either of the two stations. The data 

 for the two half years were taken on slightly different frequencies as 

 is indicated on the figure. Unfortunately, during the month of July 

 only two weeks data were taken on each of the frequencies, namely, 

 52 and 65 kilocycles, and these data were taken a year apart, namely in 

 1924 and in 1925. In order to give some idea of the location noise 

 improvement for the month of July we have averaged in the same 

 way the four weeks data thus obtained, and plotted the result as a 

 broken line. Fortunately, the improvement of the more northerly 

 location is, in general, large during the overlapping business day of 

 England and the United States. 



'"New York's New 10,000,000 Zone," Literary Digest, 95, 12, p. 14; Dec. 17, 

 1927. 



* G. W. Pickard, "Static Elimination by Directional Reception," Proc. I. R. E., 

 8, 358; October, 1920. 



