THE CALCULATION OK VKHTICAL CON Kit AC 10 



151 



These equations are plotted in Figure 50. From 

 equation (63) : 



4(A/) a 



5,280 X 4.92 X dx 



= 0.000077 



(hi'V- 



DISTANCE d t IN MILES 



Figure 51. Reflection area graph. 



Reading values of hx' and dx from Figure 50 and sub- 

 stituting in the above equations, curves of n and d x 

 are plotted in Figure 51. From these two curves 

 may be read the values of hx' and dx corresponding 

 to integral values of n. The calculation of y' and 8 

 from equations (60) and (61) are conveniently per- 

 formed by arranging columns as shown in Tables 

 6 and 7. 



For purposes of comparison with equation (62) 

 the last column gives values of y computed by means 

 of equation (57). In Table 6 the error in the figures 

 computed from equation (57) is seen to be consider- 

 ably below n = 10; for higher values of n the two 

 formulas tend to show fair agreement. In Table 7 

 the disagreement is marked even at n = 23 indicat- 

 ing that equation (57) is unsuitable for high sites. 



The lobe angles are shown in Figures 52 and 53. 

 The lines of constant altitude over the modified 

 earth are plotted from equation (49). The lobe 

 angles are constructed by drawing radial lines from 

 the center of the antenna, while the height in feet 

 at a given distance is obtained by multiplying y 

 (in radians) by 5,280 times this distance in miles. 

 The lines have not been drawn close in because of 

 the crowding and because they actually start near 



