Composite electromagnetic wave absorber made of soft magnetic material and polystyrene resin and control of permeability and permittivity

Abstract: The frequency dependences of the relative complex permeability , the relative complex permittivity and the absorption characteristics for composite electromagnetic wave absorbers made of polystyrene resin and sendust particles or permalloy particles were investigated in the frequency range from 1 to 40GHz. The size of sendust particles was varied between approximately 5 and 20μm and the particle size dependence of was observed. The value of was shown to be controlled by adjusting the particle size of sendust, and an electromagnetic wave absorber with a flexible design was proposed. A metal-backed single-layer absorber made of sendust particles or permalloy particles absorbed more than 99% of electromagnetic wave power at frequencies above 20GHz. In addition, a composite made of 5μm particles exhibited a return loss of less than −20dB in the frequency range of not only several GHz but also above 30GHz. [Copyright &y& Elsevier]