Third order intermodulation performance of above resonance circulators

One topic which has received little attention in the engineering literature is the optimisation of third order intermodulation products in stripline ferrite circulators biased above ferromagnetic resonance. A technique which may be used to gain insight into possible adjustments of this parameter is to construct an experimental mode chart detailing the resonant frequency variation of the first pair of degenerate counter-rotating modes in this sort of device and the main Kittel resonance as the external magnetic field is varied. In this paper a description of the intermodulation effect in terms of a nonlinear transfer function is presented as a preamble to the construction of experimental mode charts for two different gyromagnetic resonators and a study of their associated intermodulation performance.