The propagation of radio waves

The paper gives the results obtained from a systematic study of the received intensities of various long-wave transmitting stations at four receiving stations over a period of nearly two years. The weekly averages of the results are studied, and it is shown that they are inconsistent with any law of steady decay. The results also show very marked periodic variations. It is suggested that all the observed effects can most easily be explained on the assumption of an upper refracting layer. This is supported by the results obtained from plotting an intensity distance curve in detail by means of a portable set, and by the study of the systematic changes which take place daily during the sunset period. Various conclusions are drawn from these results, but it is pointed out that considerable further experimental investigation of many of the observed phenomena is necessary.