Long distance VHF-UHF tropospheric field strengths and certain of their implications for radio communications (abstract)

Sufficient knowledge of normal VHF-UHF tropospheric field strengths has been obtained for distances far beyond the radio horizon to enable sensible planning of communication circuits having ranges of some 200-250 statute miles. It is desirable, of course, to exploit this propagation mode to the greatest possible distance and this requires a detailed knowledge of the path loss to distances beyond 200 mi. Data available from long path length measurements made by the Central Radio Propagation Laboratory of the National Bureau of Standards, Bell Telephone Laboratories, the Lincoln Laboratory of the Massachusetts Institute of Technology (MIT), and the Propagation Laboratory of the US Air Force Cambridge Research Center have been subjected to analysis and comparison. As a result, it appears that a good estimate of temperate latitude transmission loss can now be made within the' 100-500 Mcps region to distances of 400 mi, and usable estimates to 600 mi.