Electromagnetic shielding properties of soft magnetic powder–polymer composite films for the application to suppress noise in the radio frequency range

Electromagnetic absorption characteristics in the near- and the far-field regime were evaluated from measurements of power loss by the coaxial transmission and reflection method and the microstrip line method, respectively, for high-density soft magnetic Fe–Al–Si alloy–polymer composite films that were highly effective in the radio frequency (RF) range. The electromagnetic absorption in the near- and the far-field regime for the soft magnetic metal–polymer composite films was greatly dependent on the film density. The electromagnetic absorption in the RF range significantly increased with increasing film density, which was caused by the increase of the magnetic permeability and the electrical conductivity. As a result, the high-density soft magnetic film showed excellent electromagnetic absorption for the near- and the far-field electromagnetic shielding and was applicable as an electromagnetic absorber for high-frequency devices operated over 0.1 GHz.