Low Bias Field Hexagonal Y-Type Ferrite Phase Shifters at ${K}_{U}$ -Band

A microstrip line fabricated on a single crystal hexagonal Y-type ferrite substrate was utilized to achieve phase shifts of ~65deg/cm at K_U-band with an external bias field of only 100 Oe. This approach utilizes the rapid variation of the Y-type ferrite tensor permeability near the ferromagnetic antiresonance frequency. The magnetic and microwave properties of the substrate material were characterized by vibrating sample magnetometry and ferromagnetic resonance measurements. Numerical methods based on Galerkin´s approach adapted to spectral domain were utilized to model the performance of the device while taking into account the correct form of the tensor magnetic permeability of the anisotropic and gyromagnetic substrate material. Good agreement between the numerical results and experimental data was obtained. A miniature electromagnet, based on a Metglastrade laminated yoke to minimize demagnetizing fields, was fabricated. Phase shifts of 50deg/cm were achieved with continuous drive currents of only 100 mA.