Numerical analysis of dominant loss parameters of ferrite thin films for conduction noise absorption in microstrip lines

摘要

The dominant power loss mechanism from conduction noise in a microstrip line was verified by investigating the effects of electrical conductivity and magnetic loss on noise reflection and transmission, and of power absorption in thin film absorbers (Ni-Zn ferrite thin film with high electrical resistivity, and electrically conductive ITO and Fe_3O_4 films). Using a simulation model of a microstrip line attached by thin films, the S parameters and power absorption were calculated for the frequency range from 0.05 to 3 GHz. Even if the film has a large value of magnetic loss due to ferromagnetic resonance, it is predicted that power dissipation by magnetic loss would be quite small, as was predicted for the Ni-Zn ferrite films. For the conductive and magnetic Fe_3O_4 thin film with similar magnetic loss dispersion, the contribution of magnetic loss to total power loss is also quite small. The values of S_(11), S_(21), and power absorption were almost the same as that for conductive ITO thin film of which the electrical resistivity was on the same order as that of the Fe_3O_4 thin film. The simulation of power absorption by the hybrid structure of ITO/Ni-Zn ferrite and ITO/Fe_3O_4 also supports this conclusion.