A novel nanostructured microstrip device for tunable stopband filtering applications at microwaves

This letter presents a novel microstrip structure using a nanoscale porous substrate filled by a ferromagnetic material, forming an array of nanowires perpendicular to the ground plane. When compared with photonic bandgap str uctures, the stopband behavior is created here by a gyromagnetic resonance phenomenon in the metallic nanowires. This resonance is tuned by means of a de magnetic field parallel to the nanowires, in a very good agreement with the gyromagnetic theory, Also, tuning can be achieved over more than one o ctave, because the nanoscale geometry ensures that fields penetrate into th e whole wire area up to 40 GHz. Other advantages are detailed in the letter .