#Irregular Terrain Model (ITM) (Longley-Rice) (20 MHz – 20 GHz) (from NTIA) This is a mirror (July 22, 2015) from NTIA ITM
#Abstract The Institute for Telecommunication Sciences (ITS) model of radio propagation for frequencies between 20 MHz and 20 GHz (the Longley-Rice model) (named for Anita Longley & Phil Rice, 1968) is a general purpose model that can be applied to a large variety of engineering problems. The model, which is based on electromagnetic theory and on statistical analyses of both terrain features and radio measurements, predicts the median attenuation of a radio signal as a function of distance and the variability of the signal in time and in space.
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