E-plane finline circulator using coupled H-plane turnstile resonators

Junction circulators using finline circuits may be realised by employing planar or turnstile ferrite resonators. The authors describe a finline turnstile circulator at 21 GHz, comprising a directly coupled evanescent junction of three E-plane WR42 waveguides symmetrically loaded by H-plane open gyromagnetic resonators. The degenerate counter-rotating eigenvalues of the device correspond to the even solution of two coupled quarterwave long resonators; the junction is separately cut-off for the in-phase eigenvalue.