UL TRA -SHOR T- WA VE PROP A GA TIO N 



259 



When the propagation is through built-up areas instead of over level 

 terrain the condition is more complicated. Even here, however, for 

 terminals well above the tops of buildings, theoretical considerations ^ 

 indicate that the same explanation of direct and reflected waves is 

 valid. Data presented by Jones ^^ may be used as a verification for 

 this explanation even for transmission over buildings. Fig. 11 of 

 his paper shows that for heights between 170 and 1,500 feet the field 

 is proportional to the height in accordance with equation (5). When 

 the terminals are lowered within the building region, the field should 

 decrease more rapidly than proportionally with the height above the 

 ground. In fact, data presented in Fig. 4 indicate that with one 



u. 20 



18 20 ZZ 24 26 28 30 32 34 



FIELD STRENGTH IN DECIBELS ABOVE 1 MICROVOLT PER METER 



Fig. 4 — Variation of field received at Berkeley and Stuart Streets with antenna 

 height. Curve A shows the variation with height above the roof while Curve B 

 shows the variation with height above the ground. The slope of the broken line 

 indicates a linear relationship between field and height. 



1 Loc. cit. 



*" L. F. Jones, "A Study of the Propagation of Wave-lengths between Three and 

 Eight Meters," Proc. I. R. E., Vol. 21, pp. 439-486, March, 1933. 



