124 



CALCULATION OF RADIO GAIN 



The radio gain can therefore never be more than 

 6 db greater than the free-space gain with the same 

 antennas. 



If, however, one antenna is low, h < h^, and the 

 other is very high, h > iOhc, the method discussed 



four tables of computations are given. Table 11 

 gives the values of certain quantities, for a wide 

 range of frequencies and for very dry soil, which are 

 independent of polarization. Those quantities which 

 are dependent on polarization are given in Table 12. 



210 



170 

 160 



150 

 140 

 130 

 120 



ui no 



m 



S 100 



o 



90 



80 

 70 

 60 

 50 

 40 

 30 

 20 

 10 

 

 -10 



10 100 



HEIGHTS h, OR hj IN METERS 



Figure 60. First mode height-gain factors for transmitter and receiver. 



fails since the height-gain factors are based on the 

 first mode only. In this event, either the methods 

 outlined in Section 5.7.5 must be employed or the 

 radio gain at low elevations must be connected 

 graphicaUij with the value obtained in the optical 

 region for the first maximum. 

 As an aid to the computer in checking his results, 



Table 13 gives detailed calculations for ground level 

 radio gain for doublets for a wavelength of X = 1.0 

 meter, while Table 14 gives the first mode height- 

 gain factors for the same wavelength. 



Similar charts and tables may be prepared easily 

 for transmission over other types of earth for a 

 similar range of frequencies. 



