22 



BF.U. SYSTEM TllCIISlCAL JOIRSAL 



which ihc iiierKV is not wiu.illy dividi-tl l»tl\veen the line ant! net- 

 work ami the im|x-<lanre of the network is either greater thim or 

 less than that of the line in a ixrtain ratio. 



Throunh unfaniiliarity with the principles involvid the iiiveiUors 

 sometimes assume that an approximate halance such as might be 

 obtained by using a simple resistancx- is sulTieient lo meet all re- 

 quirements. .\onc of these- arrangements, however, can avoid the 

 effects <»f departures of the line impedane-c from the values for which 

 the networks are designetl nor cun they in-tter the performance of 

 the present refx-aters in respect lo the effects of impedance lieparturcs. 

 Usually such circuits are inferior in .some imix>rtanl respect to the 

 arrangements now in us*.-. 



2. Circuits usiii^ Rectifitrs. In one t\pe of circuit the inventors 

 propose to use rectifiers to prevent the output energy of one amplifier 



Fig. 6 



.iiiiiiK ii|«>n the input circuit of liie oilitr. .\ simple diagram illus- 

 trating the ojKration of this scheme is given in Fig. 0. Rectifiers are 

 placetl in series with the input and output circuits of both amplifiers 

 and [xjled in the directions indicated by the arrow heads which point 

 in the direction the rectifier is supposed to permit current to pass. 

 It is argued that the rectifier in the output circuit of each amplifier 

 permits only currents of one |X)larity to enter the line and that the 

 rectifier in the input circuit of the opposite amplifier is so poled that 

 these cnitput currents cannot [wss it into the input circuit and, there- 

 fore, singing cannot iKcur. 



If a wave arrives, for example over the line west, the p.jsiiive half 

 waves |xiss through the rectifiers 1 and 2 into the input of the e.ist 

 Uiund and the output of the west bound amplifier respectively. 

 The negative half wavc-s are suppressed by the rectifiers. This is 

 illustr.ited by I-"ig. 7 which shows the wave arri\ing over the line and 

 Fig. S which shows the part of the wave which enters the amplifiers. 



That jxirtion which reaches the output of the west bound amjili- 

 fier IH hist while the [xirtion which reaches the input of the east bound 



