. The Bell System Technical Journal . ses with increaining ^ Lloyd Espenschied, C. N. Anderson und Austin Bailey, Transatlantic Radiotelephone Transmission, Bell System Tech. Jour., 4, 459; Juli 1925. Proz. I. R. E.,14, 7; FEB. 1926. ^ Ralph Bown, C. R. Englund, und H. T. Friis, Radio Transmission Measurments, Proc. I. R. E., 11, 115; APRIL, 1923. 312 GLOCKE SYSTEM TECHNISCHE JOURNAL Frequenz, zuerst schnell und dann langsamer, fast konstant nach dem Passieren der Frequenz von 40 Kilocycles. Aus den so erhaltenen Werten von Signal und Rauschen wurde die Signal-Rausch-Ratio berechnet, ein
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. The Bell System technical journal . ses with increasing ^ Lloyd Espenschied, C. N. Anderson, and Austin Bailey, Transatlantic RadioTelephone Transmission, Bell System Tech. Jour., 4, 459; July, 1925. Proc. I. R. E., 14, 7; Feb., 1926. ^ Ralph Bown, C. R. Englund, and H. T. Friis, Radio Transmission Measure-ments, Proc. I. R. E., 11, 115; April, 1923. 312 BELL SYSTEM TECHNICAL JOURNAL frequency, at first rapidly and then more slowly, being almost constantafter passing the frequency of 40 kilocycles. From the values of signal and noise so obtained, the signal-to-noiseratio has been computed, and is also plotted in Fig. 2. The curve ofsignal-to-noise ratio reaches a maximum near 44 kilocycles whichwould seem to be the optimum frequency for daylight transmissionfrom the Rocky Point station to England. This is not strictly thecase, however, since there is some evidence that a phenomenon existswhich makes frequencies in the vicinity of 40 kilocycles particularlypoor for the transatlantic path. Data published by Anderson ^ tend. 30 40 50 60 FREQUENCY - KILOCYCLES Fig. 2—Variation of signal, noise, and signal-noise ratio with frequency. Trans-mission from U. S. A. to England. 85.9 kw. supplied to antenna of Rocky Pointcharacteristics. to show that the field strength is distinctly subnormal in the vicinityof 44 kilocycles and remains approximately constant from that fre-quency up to about 60 kilocycles, where the observed values agreefairly well with the calculations. (See later in this paper.) 2. Band Width of the Transmitting Antenna. Since the output ofthe transmitting set is at a high power level, the circuits coupling itto the antenna must be of the simplest type to reduce the loss to aminimum. In view of this requirement, the antenna constants largelydetermine the band width of the antenna system. At frequenciesmuch lower than 60 kilocycles it was not possible to secure a sufficientwidth of band even for commercial telephony from the Rocky Point C. N. Anderson, Corr
