76 THE BELL SYSTEM TECHNICAL JOURNAL, JANUARY 1952 



Fig. 6 — Representative photographs of angle-of -arrival observations on the 

 Murray Hill-Crawford Hill path, (a) Normal da}', (b) Two elevated paths. Sept. 

 8, 1950; 9:23 p.m. (c) Three elevated paths. Aug. 27, 1950; 1:11 a.m. (d) Multiple 

 paths. August 26, 1950; 11:00 p.m. (e) Wide angle "fill-in". Aug. 26, 1950; 11:04 

 p.m. (f) Abnormal water reflection. Sept. 8, 1950; 11:28 p.m. 



During these multiple-path conditions, the recordings of the 4195-mc 

 transmission generally show the broad maxima and sharp minima charac- 

 teristic of wave interference. 



Figure 6(d) shows a case in which the various paths are not completely 

 separated while Fig. 6(e) (taken four minutes later) shows that energy 

 is being received almost without variation over a vertical angle of 0.4°. 

 This may represent a number of ray paths which would be separable by 

 a narrower-beam antenna, or it may indicate a focussing or trapping 

 phenomenon. Often when the type of transmission illustrated by 6(e) 

 is present, the recorded 4195-mc signal may be as much as 12 to 15 

 decibels above the free space levels. 



