Suppressing self-modulation in vacuum microwave delayed-feedback oscillators by using additional feedback

Self-modulation instability is typical for special distributed oscillators especially with time delayed feedback. This instability results in generation of multiple frequencies or even spread spectrum chaotic signal. In this paper, we propose a method for suppressing the self-modulation that is a modification of the well-known time-delayed controlling chaos technique. Numerical results for delayed feedback klystron and traveling-wave tube oscillators are presented showing that application of the method allows stabilization of unstable single frequency regimes and improves performance of the oscillators.