Prediction of Transmission Loss over Transhorizon Tropospheric Propagation Paths in the Indian Subcontinent

152-157A method of prediction of transmission loss over transhorizon tropospheric propagation paths, evolved as a result of extensive radio wave propagation and radio meteorological studies in India is discussed. The technique of prediction essentially depends upon observed correlation of field strength with initial gradient of refractivity and an empirical relationship of this parameter with the Eklund-Wickerts' analytical model [Eklund, F. & Wickerts, S., Radio Sci., 3 (11) (1968), 1066]. The statistical distribution of field strength is shown to be predictable from statistical distribution of initial refractivity gradient. Observed cumulative distribution of hourly median field strength over two specific paths at two radio frequencies has shown better agreement with this prediction system than with NBS 101