Institute for Telecommunication Sciences
the research laboratory of the National Telecommunications and Information Administration

G. D. Gierhart; M. E. Johnson

Abstract: This report provides a description of the computational details in the IF-77 (ITS-FAA-1977) radio wave propagation model. The IF-77 model is useful in estimating service coverage for radio systems operating in the 0.1 to 20 GHz frequency range. It is applicable to many air/air, air/ground,air/satellite, ground/ground, and ground/satellite systems. Irregular terrain and propagation beyond the line-of-sight range are considered in the model. However, the terrain feature is keyed to the lower (or facility) antenna and the radio horizon for the upper (or aircraft) antenna is (1) determined from the facility horizon obstacle (common horizon) or (2) taken as the smooth earth radio horizon when a common horizon is negated by the earth's bulge. Previous publications concerning IF-77 include (l) an applications guide for computer programs that use IF-77, (2) an extensive comparison of predictions made using IF-77 with measured data, and (3) an atlas of propagation curves applicable to aeronautical systems. Details concerning the computer programs are not included in this report.

Keywords: propagation model; Transmission Loss; air/air; air/ground; earth/satellite; protection ratio

To request a reprint of this report, contact:

Lilli Segre, Publications Officer
Institute for Telecommunication Sciences
(303) 497-3572

For technical information concerning this report, contact:

Paul M. McKenna
Institute for Telecommunication Sciences
(303) 497-3474

Disclaimer: Certain commercial equipment, components, and software may be identified in this report to specify adequately the technical aspects of the reported results. In no case does such identification imply recommendation or endorsement by the National Telecommunications and Information Administration, nor does it imply that the equipment or software identified is necessarily the best available for the particular application or uses.

Back to Search Results