WAVEGUIDE TRANSMISSION 



311 



If the wave is subject to an attenuation of a units per unit distance, 

 possibly due to resistance in the wires, the corresponding components of 

 E and H are equally attenuated. Either component may be expressed by 

 an equation of the type 



E = E, 



oe 



sm — \z 

 \ 



vt) 



(6.2-4) 



This is a very special form of certain equations appearing in Sections 3.2 

 and 3.3. 



a = o 



distance— z 



Fig. 6.2-4. Effect of attenuation on an advancing wave front. 



If the attenuation is negligible, then « = and the term e^"' will be unity. 

 Equation 6.2-4 will then reduce to 6.2-2. If, on the other hand, the attenua- 

 tion is considerable, the product of a times z will increase rapidly with dis- 

 tance, and the factor <? "^ will have the effect of reducing the electric 

 intensity E prevailing at various points along the line. Figure 6.2-4(a) illus- 

 trates the variation, with distance, of the electric intensity E for an un- 

 attenuated wave a = 0. There is included for comparison purposes the case, 

 a = 0.1. Figure 6.2-4(b) shows the effect of this rate of attenuation on waves 

 that have traveled for some distance. It is significant that moderate amounts 

 of attenuation have little or no effect on wavelength. 



