Papers by Keyword: Isolated Model

Abstract: In order to design a ferrite absorber that can be used at frequencies of several GHz, the frequency dependences of the relative complex permeability μ_r^*, the relative complex permittivity ε_r^*, and return loss were investigated for a composite made of Ni-Zn ferrite and SiO₂. When ferrite particles were dispersed and isolated in an SiO₂ medium, the frequency dependence of μ_r^* was different from that for a composite made of SiO₂ particles dispersed and isolated in the ferrite medium. Moreover, when ferrite particles were isolated and a suitable mixture ratio of ferrite and SiO₂ was selected, the return loss was less than −20 dB at frequencies of several GHz. The dispersion states of ferrite and SiO₂ particles are thus important factors to design an absorber, and improvement in the absorption characteristics of the ferrite tile which is used as a practical absorber could be achieved using a composite made of Ni-Zn ferrite particles dispersed and isolated in an SiO₂ medium.

Abstract: It is found through simulation that composite electromagnetic wave absorbers made of Ni-Zn ferrite and SiO2 particles, which are isolated in the continuous medium of Ni-Zn ferrite, show good absorption. In particular, absorbers show absorption in the frequency regions both below and above 1 GHz for the mixing ratio of SiO2 of 80 mol%. To simulate the complex permeability of the composite materials, we considered some arrangements of SiO2 in the Ni-Zn ferrite medium. Measured values of complex permeability are close to simulated ones above 1 GHz.

Abstract: It is found through simulation that electromagnetic wave absorbers made of composites of Ni-Zn ferrite and SiO2 particles, which are isolated in a continuous medium of Ni-Zn ferrite, show absorption in the frequency regions both below and above 1 GHz. The measured complex permeabilities are close to simulation values above 1 GHz. Both absorbing bandwidth and center frequency of the composites are close to the desired values expected from the simulation result.