Tropospheric Scatter Path Loss Tests - Florida Bahamas

Abstract

Telephone service between the United States and the Bahama Islands is now provided by means of high-frequency radio systems working in the 2-7 mc range. To handle properly the large volume of traffic during the peak winter season requires that more than the present nine circuits be provided. The lack of available frequencies in the 2-7 mc range, together with the comparatively poorer grade of facility obtained from these radio systems, makes it desirable to investigate other methods of providing telephone facilities. The fact that the present Miami-Havana tropospheric scatter system is performing so well, and that the distance from Miami to Nassau is the same as that to the Cuban terminal, made this type of system very attractive. At the time the Cuban system was being developed, klystron tubes capable of high outputs above 1000 mc were not available. For this reason, the Cuban system was designed to operate in the 700-900 mc range. Since that time tubes capable of high output levels at frequencies above 2000 mc have been developed, and it was considered desirable to operate at these higher frequencies rather than in the lower part of the UHF spectrum. Path loss tests were made over a nineweek period on the Florida-Nassau path using a frequency of 1970 mc. These tests are discussed and some comparisons are drawn between them and the path loss tests made to Cuba at 800 mc two years earlier. The Nassau tests indicated that a satisfactory 60-channel radio system could be provided through use of 10-kw transmitters and 30-foot parabolic antennas.