Self-biased circulator/isolator at millimeter wavelengths using magnetically oriented polycrystalline strontium M-type hexaferrite

A self-biased circulator/isolator operating at millimeter wavelength has been designed, fabricated, and tested. The ferrite material used in the device, magnetically oriented polycrystalline strontium M-type hexaferrite (SrFe/sub 12/O/sub 19/, SrM), was characterized by vibrating sample magnetometer and ferromagnetic resonance. The measurement of S-parameters indicated that at 41 GHz, the isolation was 28 dB and the insertion loss was 4 dB.