November 1971 | NTIA Technical Report OT/TRER 21
Gary D. Gierhart; Albrecht P. Barsis; Mary Ellen Johnson; Evelyn M. Gray; F. M. Capps
Abstract: An analysis is presented of air-ground radio wave propagation measurements, which were performed using an airborne transmission source at approximately 6,400 m above msl. Receiving antennas were slightly within and beyond line-of-sight of the airborne transmitters. Received signal level data were obtained on 82 3. 75 MHz and 84 7. 75 MHz. Data were analyzed for short-term and long-term statistics of basic transmission loss. Long-term fading range statistics were compared with values calculated using a modified Longley-Rice model and good (~1%) agreement was obtained. This model appears to underestimate the long-term median transmission loss by about 3 dB.
Keywords: air-to-ground propagation; propagation loss; tropospheric propagation; air-to-ground transmission
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