118 



CALCULATION OF RADIO GAIN 



than 10 meters 1 5 1, as given by Figure 53 for vertical 

 polarization, is large except in the VHF range over 

 sea water, t^ = 80, cr = 4. 



The ground constants t^ aiid a for water and 

 various t3^pes of earth are gi\'en in Table 10. For 

 \ <\ the groinid material is a dielectric earth. 



Table 10. Ground constants. 



Type of groimd 



Sea water er = SO a = i mhos per metei' 



Freshwater e, = 80 <r =5 X lO"'^ 



Aloist soil er = 30 a = 0.02 



Fertile grouml t,- =1.5 u = 5 X 10"'' 



Rocky ground t^ = 7 a = lO"'^ 



Dry soil e^ = 4 <t = 10-2 



Very dry soil tr = i a = 10"^ 



K = 



60cr 



0.33 m 



267 



25 



50 



117 



6.7 



66.7 



3. The mode numhcra t„. These numbers are given 

 lx4o\v for the two limiting values for 5 = (infinite 

 conductivity or X— > oo), and for 5 = co, i.e., the dielec- 

 tric earth. 



10 10' 



X IN METERS 



10- 



10* 



Figure 54. Phase of 6 for vertical polarization. See Table 10. 



