64 



CALCULATION OF RADIO GAIN 



TRANSMITTER LOW 



optical-intcrtesemce: region 

 low antenna region 



LINE OF SIGHT 

 TRANSITION 



FIRST /^ 

 MODE 



TRANSMITTER ELEVATED 



OPTICAL-INTERFERENCE REGIC 



TRANSITION 



LINL Of SIGHT 



Figure 3. Field regions as i-elated tii traiiismitter heights for horizontal polarization or ultra-short waves. Low antenna 

 region = X</ > 2/^/1:; /u, h < SOX^-'S. 



>" 



d IN KILOMETERS 



Figure 4. Variation of field strength with distance for propagation on vertical polarization with a wavelength of 70 cm 

 over dry soil. The point "due to minimum" results from minimum in reflection coefficient at the pseudo-Brewster angle. 



