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BELL SYSTEM TECHNICAL JOURNAL 



terminal to the south or southwest. Here the intervening ground is 

 fairly level, and there are no high hills that can be used for the receiving 

 terminal. The third type of path is mostly over water to points on 



ICX30 1500 



altitude;- METERS 



Fig. 4 — Field strength as a function of receiver altitude at a distance of 77 km. 

 The path was mostly over water. The arrow T shows the altitude at which the line 

 of sight, neglecting refraction, becomes tangent to the earth's surface. 



1000 

 ALTITUDE- 



Fig. 5 — Field strength as a function of receiver altitude at a distance of 141 km. 

 The path was mostly over water. The arrow T shows the altitude at which the line 

 of sight, neglecting refraction, becomes tangent to the earth's surface. 



Long Island. Typical profiles of over-land paths are shown in 

 Fig. 6. 



The experimental results of transmission over these paths, together 

 with some of their characteristics, are given in the table of Fig. 7. 

 In the last three columns is given the received field in decibels below 



