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BELL SYSTEM TECHNICAL JOURNAL 



Equations (9.9) and (9.11) give the behavior of a reflex oscillator with 

 zero output circuit loss as the load is changed. It is interesting to plot 

 this behavior on a Smith chart. Such a plot is known as a Rieke diagram 

 or an impedance performance chart. Suppose we iirst make a plot for 

 A^ = 0. This is shown in Fig. 32. Constant p contours are solid and, as 



Fig. 32. — Theoretical Rieke diagram for a reflex oscillator operating with optimum 

 drift angle. The resonator is assumed lossless. Admittances are normalized in terms of 

 the small signal electronic admittance of the oscillator so that oscillation will stop for unity 

 standing wave. 



can be seen from the above, they will coincide with the constant conductance 

 lines of the chart. Constant frequency curves are dashed and, for M = 0, 

 they coincide with the locii of constant susceptance. The numbers on the 

 frequency contours give values of (2M/ye)(Aco/wo). The choice of units is 

 such that Gi = 1 means that the load conductance is just equal to small 

 signal electronic conductance which, it will be recalled, is the starting condi- 

 tion for oscillation. Hence, the d = 1 contour is a zero power contour. 

 Any larger values of Gi will not permit oscillation to start, so the Gx contour 

 'P. H. Smith, "Transmission Line Calculator," Electronics, Jan. 1939, pp. 29-31 



