Suppression of Higher Order Modes in Waveguide-Junction Circulators Using Coupled Open Dielectric Resonators (Letters)

It is well known that some waveguide circulators exhihit an unwanted spurious mode within their passband, which limits their insertion loss and bandwidth. This mode is identified as the TE_0,1,delta one in the case of the waveguide junction which relies on the TM_1,1delta, mode for its operation. The influence of the saturation magnetization on the separation between the two modes is studied in detail. A mode suppressor is also described which decouples the coupled TE_0,1,delta mode without altering the frequency of the circulation ones. This suppressor consists of a thin metal ring placed on the open face of one of the ferrite disks.