Accession Number:

AD0417196

Title:

PRELIMINARY RESULTS OF UHF AIR-TO-GROUND PROPAGA TION MEASUREMENTS,

Descriptive Note:

Corporate Author:

NATIONAL BUREAU OF STANDARDS BOULDER COLO

Personal Author(s):

• Barsis,Albrecht P.

Report Date:

1963-07-01

Pagination or Media Count:

16.0

Abstract:

The National Bureau of Standards is engaged in a measurement program of transmissions in the UHF band, which originate from airborne transmitters at a nominal altitude of 23,000 ft above east central Indiana. Several receiving stations within and slightly beyond the radio horizon are used. The data are being analyzed to show long and short-term transmission loss variations over these paths including estimates of the effects of the flight pattern of the transmitting aircraft on the character of the received signal. Initial results show that long-term variability of basic transmission loss as measured by percentile rof hourly or daily medians is essentially in agreement with predictions. The absolute re ceived signal levels, however, are mostly below free-space values for the distances concerned, necessitating detailed terrain analyses along the paths in order to arrive at an appropriate prop agation model. The character of short-term fading at the various receiving sites depends quite markedly on the direction of the flight pattern axis. Maximum fading range is observed for the Milwaukee receiving station, where Lake Michigan constitutes an almost ideal reflecting surface. Author

Descriptors:

• *PROPAGATION
• AIRCRAFT
• ATTENUATION
• TERRAIN
• FLIGHT PATHS
• REFLECTION

Subject Categories:

Distribution Statement:

APPROVED FOR PUBLIC RELEASE