Dual H- and E-Field Tunable Multiferroic Bandpass Filter at ${\rm K}_{U}$ -Band Using Partially Magnetized Spinel Ferrites

A compact dual H- and E-field tunable multiferroic bandpass filters with low magnetic fields using partially magnetized nickel ferrites were designed, fabricated and characterized. Compared to widely used yttrium iron garnet material with a low saturation magnetostriction, nickel ferrite with a much larger saturation magnetostriction was used in this work, which led to higher frequency tunability under electric field. The multiferroic tunable bandpass filters with a NiFe₂O₄ ferrite/lead magnesium niobate-lead titanate heterostructure at Ku-band, exhibits an H-field tunable of 5.7% under less than 150 Oe bias magnetic field, and an E-field tunable operating frequency range of 270 MHz (2.1%). These dual H- and E-field tunable bandpass filters using partially magnetized spinel ferrites with low magnetic fields lead to Ku-band compact tunable bandpass filters with low power consumption.