Injection Locked Oscillator Theory for Frequency Selective Limiters

Ferrite frequency selective limiters (FSL) can be realized as a transmission line coupled to a magnetized ferrite medium. Above a critical threshold power level, spin wave modes near one half the applied frequency grow exponentially and couple strongly to thermal phonons, resulting in an increase in RF power absorption at frequencies near that of the high level signal. The measured absorption is asymmetrical around the strong signal. Treating the FSL as a manifold of injection locked oscillators provides a possible explanation for this asymmetry.