Broadband RF Noise Suppression by Magnetic Nanowire-Filled Composite Films

The characteristics of the electromagnetic noise suppression have evaluated using magnetic nanowire-filled composite film on a microstrip line in the broadband radio-frequency range from 0.5 to 20 GHz. The ferromagnetic resonance frequency and the relative complex permeability with the change of aspect ratio were calculated by Kittel´s and Landau-Lifshitz-Gilbert equations. The FMR frequency is gradually increased with the increment of aspect ratio (up to 50) of magnetic nanowire. When the magnetic nanowires were mixed with various aspect ratio in composite, the FMR frequency exhibited the broadband frequency regions with 10-28 GHz, 5-14 GHz, 2.5-7 GHz, and 1-2.7 GHz for the change of magnetizations (4piM_s: 20, 10, 5, and 2 kG), respectively. Using the calculated FMR frequency profile, the power losses were obtained in broadband frequency region. The transmission power absorption of the composite film on microstrip line was simulated using a 3-D FEM HFSS simulation program. The microstrip line model was composed of Cu conductor line and grounded dielectric substrates, which was designed by IEC standard (IEC 62333-2). The conduction electromagnetic noise was suppressed by the various aspect ratios of the magnetic nanowire-filled composite films in broadband frequency region.