Propagation prediction techniques and data required for the design of trans-horizon radio-relay systems

considering a) that for the proper planning of trans-horizon radio-relay systems it is necessary to have appropriate propagation prediction methods and data; b) that methods have been developed that allow the prediction of most of the important propagation parameters affecting the planning of trans-horizon radio-relay systems; c) that as far as possible these methods have been tested against available measured data and have been shown to yield an accuracy that is both compatible with the natural variability of propagation phenomena and adequate for most present applications in system planning,