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Incorporation of Ferromagnetic Metallic Films in Planar Transmission Lines for Microwave Device Applications



Nicholas Cramer, D. Lucic, Dave K. Walker, Robert E. Camley, Zbigniew J. Celinski


We construct a series of microwave transmission lines in microstrip and co-planar waveguide. These structures incorporate metallic ferromagnetic and dielectric films and therefore exhibit strongly frequency-dependent attenuation and phase-shift effects. The lines have maximum attenuation peaks occurring at the ferromagnetic resonance frequency. The frequency position of these peaks increases with increased applied magnetic field. This allows construction of band-stop filters with tunable frequencies. For our devices that incorporate Fe as the ferromagnetic material, the resultant band-stop frequencies range from 10 GHz to 20 GHz for applied fields up to only 80000A/m (1000 Oersted). For devices using permalloy, the band-stop frequency range is in the 5-10 GHz range for applied fields less than 80000 A/m. We construct devices using monocrystalline Fe films grown by Molecular Beam Epitaxy and polycrystalline sputtered permalloy films. We observe maximum power attenuation on the order of 100 dB/cm, much larger than the previously reported values of 4 dB/cm. The resonance conditions also affects the phase of the transmitted wave, causing strong phase changes above and below the resonance frequency. The result is a phase-shifter that is tunable with the applied magnetic field. We observe phase changes of over 360 degrees/cm with less than 40000 A/m applied field.
IEEE Transactions on Magnetics


ferrimagnet, ferromagnet, thin-film ferromagnet, tunable filters, tunable phase shifters


Cramer, N. , Lucic, D. , Walker, D. , Camley, R. and Celinski, Z. (2001), Incorporation of Ferromagnetic Metallic Films in Planar Transmission Lines for Microwave Device Applications, IEEE Transactions on Magnetics (Accessed June 15, 2024)


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Created June 30, 2001, Updated October 12, 2021