Evaluation of Composite Electromagnetic Wave Absorber Made of Polystyrene Resin and Permalloy or Sendust

摘要

The frequency dependences of the complex permeability (μ{sub}r){sup}*, complex permittivity (ε{sub}r){sup}*, and return loss were investigated for composite electromagnetic wave absorbers made of soft magnetic materials (permalloy or sendust) and polystyrene resin. For permalloy, two types of particle shape were used: grain-type or flake-type. The volume mixture ratio of magnetic materials was varied in the range from 40% to 70%. The values of the real part μ' and imaginary part μ" of (ε{sub}r){sup}* increased with increasing mixture ratio of magnetic materials. The frequency dependence of (μ{sub}r){sup}* for flake-type permalloy composite was similar to that for sendust composite. All absorbers showed the absorption of electromagnetic waves in the frequency range above 1 GHz.