626 



BELL SYSTEM TECHNICAL JOlRyAL 



1 he circuit of Fij:;. 116 does not tell us how (> i, varies with variation in load 

 impedance Z i. . I'urther, L and C in this circuit are changed in changing 

 Zl , and include a contribution from the inductance of the couj)ling loop 

 (which should not be very large). 



Fig. 116. — A simplified ecjuivalent circuit of an oscillator resonator. 



Several resonator parameters are vitally important in discussing reflex 

 oscillators. These will be discussed referring to Fig. 116. G i. and G« 

 have already been defined. The resonant radian frequency a-o is of course 



a-„ = (LCr'" (a7) 



A very important quantity will be called the characteristic admittance M 



M = (C/Lf- 



(a8) 



This quantity is important because at a frequency Aw off resonance the 

 admittance of the circuit is verv nearlv 



I' = G -\- jIMAw/wu 



AcO = CO — (x\) 



The "loaded" Q of the circuit \\ ill be referred to merely as Q and is 



{) = M/Gc. 

 The unloaded () is 



()„ = M/G,i 

 A quantity which may be called the "external ()"is 



(),. = M/G, 

 We see 



l/C>o+ \/Qk= 1/() 



(a9) 



(alO) 

 (all) 



(a 12) 

 (al3) 



The energy stored in the magnetic lield at zero voltage across the resonator, 

 and the energy stored in the electric field at the Nollage maximum are both 



IF., = (1/2) F'C 



= (l/2)F'M/con 



(al4) 

 (al5) 



