CONSTANT PHASE DIFFERENCE 



95 



general characteristics which can be obtained with the prescribed type of 

 inetwork. This is followed by the determination of particular choices of the 

 arbitrary constants in the expression, which will lead to the best approx- 

 imation to the prescribed ideal characteristic. The next step is to deter- 

 imine formulae for the degree of approximation to the ideal, which will be 



PHASE-SHIFTING 

 NETWORKS 



Fig. 1 — Phase-shifting networks for approximation to a constant phase diffLrence. 



Z 5 



> 



1 2 3 4 5 6 7 8 10 20 30 40 60 80 100 200 400 



FREQUENCY RATIO , Wa/^i 



Fig. 2— Variation in phase difference, when average is 90°, with a network of n sections. 



obtained with those particular values of the constants. The final step is 

 the development of a method for determining corresponding actual net- 

 works. 



From the optimum choice of constants, curves can be calculated which 

 show what can be done with a network of any given complexity (Fig. 2). 

 Then the complexity needed for any particular application can be read 

 directly from the curves. The special choice of constants also leads to special 



