Abstract
The complex dielectric permittivity (ε) and magnetic permeability (µ) of Radar Absorbing Materials (RAM) based on magnetic particles (MnZn ferrite particles) embedded in a dielectric matrix (silicon rubber) have been studied in the frequency range of 2 to 18 GHz. The relative permeability and permittivity of MnZn ferrite-silicon composites for various mass fractions are measured by the transmission/reflection method using a vector network analyzer. The concentration dependence of permittivity and permeability on the evaluated frequency range is analyzed. In a general way, the results show ε' parameter presenting more significant variation among the evaluated parameters (ε", µ", µ'). The comparison of dielectric and magnetic loss tangents (ε"/ε' and µ"/µ', respectively) shows more clearly the variation of both parameters (ε and µ) according to the frequency. It is also observed that higher MnZn ferrite content fractions favor both dielectric and magnetic loss tangents.
Highlights
Magnetic granular composites consisting of metallic or ceramic magnetic particles embedded in a dielectric matrix have been widely used in electromagnetic applications such as electromagnetic wave absorber and electromagnetic shielding materials[1]
Aiming to contribute to this area, this paper shows a study involving the evaluation of complex magnetic permeability (μ = μ’ - j μ’’) and dielectric permittivity (ε = ε’ - jε’’) behaviors of an elastomeric Radar Absorbing Materials (RAM) processed with different MnZn ferrite contents, in the frequency range of 2 to 18 GHz
The real and imaginary dielectric permittivity (ε’ and ε’’, respectively) and the permeability (μ’ and μ’’, respectively) behaviors are shown in Figures 4 and 5, respectively
Summary
Magnetic granular composites consisting of metallic or ceramic magnetic particles embedded in a dielectric matrix have been widely used in electromagnetic applications such as electromagnetic wave absorber ( named Radar Absorbing Materials, RAM) and electromagnetic shielding materials[1]. For single-layer microwave absorbers that have mainly magnetic losses, in comparison to those that have mainly dielectric losses, broader bandwidth and higher absorption at smaller layer thickness can be achieved[5]. In this way, it can be cited MnZn ferrite as a typical magnetic particle used in the magnetic RAM processing, attending the microwave frequency range. It can be cited MnZn ferrite as a typical magnetic particle used in the magnetic RAM processing, attending the microwave frequency range This magnetic particle has been widely used in the electromagnetic shielding and in RAM processing[2,6]
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