My memory of efforts in developing CCIR Recommendation 534-3: method for calculating sporadic-E field strength

Study Group 6 of the ITU Radio Communication Sector (ITU-R, formerly CCIR) deals with ionospheric propagation. The Study Group has twelve Recommendations, among which those recommending methods for calculating and predicting radio-signal strengths are the ones that telecommunications service providers need most. Rec. 534-3, concerning the method for calculating sporadic-E field strength, is one such Recommendation. Radio-wave propagation via the sporadic-E layer (Es) was expected, during the "short-wave age", to be a possible communications medium. But today, it is treated as a potential source of interference with television signals, because of its irregular behavior. The progress in studies of Es propagation characteristics, and the existence of data banks of f/sub 0/Es data (f/sub 0/Es is the critical frequency of the ordinary wave in vertical-incidence radio sounding), obtained through worldwide observations, made it possible to construct a prediction method with worldwide applicability. The author describes the birth of the Recommendation, and the efforts made towards its realization.