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BELL SYSTEM TECHNICAL JOURNAL 



Here we define 1%, as the small signal value of the admittance, and }v 

 as the magnitude of this quantity. If we plot the function Yes in a comple-v 

 admittance plane it takes the form of a geometric spiral as shown in Fig. 4. 



CONDUCTANCE, G 



Fig. 4. — The negative of the circuit admittance (the heavy vertical line) and the small 

 signal electronic admittance (the spiral) are shown in a plot of susceptance vs conductance. 

 Each position along the circuit admittance line corresponds to a certain frequency. Each 

 position along the spiral corresponds to a certain drift angle. 



Such a presentation is very helpful in acquiring a qualitative understanding 

 of the operation of a reflex oscillator. 



In Appendi.x I it is shown that the admittance of the resonant circuit in 

 the neighborhood of resonance is very nearly 



Vh = Gr + i2MAco/w 



(2.5) 



where Gr is a constant. The negative of such an admittance has been 

 plotted in Fig. 4 as the vertical line A'B'. Vertical positjon on this line is 



