Tunable high-frequency band-stop magnetic filters

We present results on Fe- and Permalloy(TM)-based microstrip microwave band-stop filters. These structures, prepared on GaAs substrates, are compatible in size and growth process with on-chip high-frequency electronics. We observed power attenuation of 100 dB/cm for Permalloy and 180 dB/cm for Fe. The insertion loss is low: 2-3 dB for Permalloy and 3-5 dB for the Fe-based structures. Our geometry includes a significant boost to the zero-field operational frequency due to the shape anisotropy of the magnetic element in the microstrip. Using the shape anisotropy, we create a Fe-based filter that operates at 11 GHz with zero applied field. (C) 2003 American Institute of Physics.