140 



COVERAGE DIAGRAMS 



in Chapter 5 yields 

 D = 



For lobe maxima 



1 



^ 



1 + 



Ih' = 



Hence 



D = 



2W 

 kaiy'T- 



1 



(37) 



(38) 



by substituting A' = {F2/Fi)pD and sin- {2/2) = 1. 

 For horizontal polarization p = 1 . Thus, 



V(?irfo yj 



1 



Fi J 



F- 



Fi 



or 



dmax — '^GA 



F. 



(40) 



(41) 



4 



1 + 



nX 



2fca(7')' 



(39) Here F2 and Fi are computed from the angles i^,/ and v 

 given by equations (62) and (63) in Chapter 5. The dis- 

 tance dmin from the transmitter base to the minimum 



30 -JO 30 60 70 



REFLECTION POINT <i, IN KILOMETERS 



Figure 9. Location of reflection point di as a function 

 of lobe number n. 



Contours of constant 7' are sho-wn in Figures 11 

 and 12 where 7' is a function of D and n\. 



RtFLECTlON POINT IN KILOMETERS CSTATIONAJ 



Figure 10. Variation in effective height hi' with 

 reflection point d,. 



point is obtained by substituting sin- (12/2) = and 

 K = {Fi/FiJD in equation (46) in Chapter 5. Thus 



6.6.6 



Construction of Lobes 



dn.in= VGWo[l-p^ 



(42) 



For horizontal polarization, the distance d,nax 

 from the base of the transmitter to the lobe max- 

 unum is calculated from eciuation (46) in Chapter 5 



The values of D to be used in equations (40), (41), 

 and (42) may be read directly from Figure 11 or 

 Figure 12, or calculated by equation (39). 



