An Investigation of Transmission on the Higher Radio Frequencies

A preliminary range chart has been constructed for telegraphic communication, 5 kw. in the antenna, at various frequencies. The conclusions upon which the range chart is based are derived from experiments made by the Naval Research Laboratory, from experiments made by amateurs, and upon such data as the Laboratory has had access to from commercial and Government sources at home and abroad. An attempt has been made to indicate in a general way the advantages and disadvantages of high frequency telegraphic transmission. Various critical regions are pointed out where new phenomena make their appearance: in particular these regions are (1) the region between 2,000 and 3,000 kilocycles where daylight ranges begin to increase with increasing frequency at the same time that the night ranges show extremely great increase and a degree of reliability which would be wholly unanticipated from obervations made at frequencies lower than 2,000 kilocycles. (2) A region around 6,000 kilocycles where an uncertainty develops during the winter nights at relatively very short ranges. (3) The development at successively higher frequencies of this uncertain range into the missing region which is most pronounced in the winter nights, and finally as the frequency is increased makes itself felt in the summer nights and at still higher frequencies even in the daytime. The development of this missing region to extensive areas is shown to take place with frequency rise to 20,000 kilocycles.