An Analysis of the Sensing Method of Automatic Frequency Control for Microwave Oscillators

An analysis is made of the type of automatic-frequency-control circuit that uses a simple cavity resonator for the stable element and either frequency modulation of the controlled oscillator or modulation of the cavity resonance frequency to obtain effective discriminator curves which give a null output for a frequency equal to the average cavity resonance frequency. An analysis is made of the complete automatic-frequency-control loop gain, including the transmission through the cavity as a function of the various parameters and the frequency-modulation swing. A discussion is presented of the best method of decreasing the pulling of the oscillator frequency by the cavity, and the pulling of the cavity frequency by a load which has a variable susceptance.