i,,//.v ()/ /ii(Mi./i iiiii'iinxi: la.ri.ii IKS 17 



.irraiigi'im-iU for i'\iiiiii_i; tin- j-cm-rator is siipposi-d iidI to rc<|uiri' 

 an api»ri'ciabli' ainouiii of power or to conslitulc an irri'nularity. 

 This gfiR-ralor tlu'H rcscinhk's tlio si-rii's iiiipr<latu°c of l'"itj. - in lli.it it 

 procliici's no ilisturbance in the line when no wa%es arc passing hut as 

 s<H>n as a wa\f arri\es the generator becomes active and produces a 



Fig. 3 



\i)ltage in series with llie line. By proper adjustment of the exciting 

 mechanism of the generator the voltage across its output terminals 

 can he made just equal to the disturbance produced by the impedance 

 element at B in Fig. 2 and so exactly reproduce the effects of the 

 irregularity. In order to do this the generator might have to absorb 

 energy from the wave passing over the line instead of giving it out, 

 but it would establish the desired \()ltage relations. 



Now as the generator has no appreciable impedance the wave passes 

 through it without interference but the e.ni.f. which it sets up ob- 

 viously sends out waves in each direction from the generator. 



On the right of the irregularity will be found one wave made up 

 of the original undisturi)ed wa\'e combined with that from the gene- 

 rator and traveling onward in the original direction. The combined 

 wave will usually be smaller than the original wave though it 

 might under some circumstances be larger and its shape might or 

 might not be altered depending upon the nature of the irregularity 

 and the character of the line. 



On the left of the irregularit\' will be found the original wa\e 

 traveling from left to right and the retk-cted w.ise tra\fling from 

 right to left. 



By a similar process of reasoning the reflection caused by bridging an 

 impedance across the line at the point B can be illustrated. In this 

 case the output terminals of the generator should be bridgetl across 

 the line and made of very high impedance. 



Any departure from the regular structure of the line such as occurs 

 at the junction of two lines of different types or where loading coils 



