G. D. Gierhart and M. E. Johnson

Abstract: Desired-to-undesired signal ratio predictions for the VHF Omnirange (VOR), Tactical Air Navigation (TACAN) and Instrument Landing Systems (ILS) air navigation aids are presented in this report. The parameters involved in the various systems are given first. Next propagation mechanisms applicable to the VHF and UHF bands are discussed together with the calculation of transmission loss and its variability. Third, the statistical nature of the desired-to-undesired signal ratio predictions is explained. Finally, the results of the study are presented in graphical form. Aircraft altitudes from 500 to 100,000 feet along with station separations from 20 to 695 nautical miles are considered. Detailed procedures, mathematical formulas, and computer programs used are discussed in the Appendices.

Keywords: interference; propagation; VHF; UHF; transmission loss; Instrument Landing System (ILS); navigation aids; Tactical Air Navigation (TACAN); VHF Omnirange (VOR)

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.

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