Frequency Pulling

the dependence of the trequency of self-oscillations in a two-resonator oscillatory system (Figure 1) on the direction of the change in the tuning of one of the resonators. As Ω₁ increases, the oscillator frequency ω increases from O toward A, and when Ω₁ decreases, ω decreases from C toward B. At the points A and B an abrupt change in the frequency occurs (the dotted arrows).

Figure 1. Change in the frequency ω of a double-circuit electrical oscillator as the frequency ω,₁ of the circuit C₁L₁, changes. The frequency ω,₂ of the circuit C₂L₂ is constant

Frequency pulling takes place when the frequencies Ω₁ and (Ω₂ are close together. It is used in technology to stabilize the frequency of single-resonator oscillators (such as a klystron). In this case the oscillator is connected to a supplementary resonator with a high quality factor. Owing to the frequency pulling the oscillator frequency ω is maintained close to the frequency of the supplementary resonator Ω₂. [9-1151-4; updated]