Uwb Rf / Microwave Ferrite Materials Research

With the 3G times coming,the telecommunication services turns to be intellective, mobile,wideband and personal from digital and comprehensive,and wideband electromagnetic interference has become more and more serious,which interferes seriously environment,health and information system.So it is very important to study the wideband anti-electromagnetic interference.In this paper,the effects of formulation and technologies and addictives on the electromagnetic properties of Ba₃Zn_xCo_2-xFe₂₄O₄₁ hexaferrites which can be used to be anti-electromagnetic interference material are investigated during 1MHz-1.8GHz and 1.8-18GHz.The main results are summarized as following.1.The effects of Zn²⁺ and Fe₂O₃ content.With the Zn²⁺ content increasing,resistivity decreases.When the Zn²⁺ content is 1.2,initial permeability and permittivity are maximum,reflection loss is minimum at low frequency.With Fe₂O₃ contentε_Fe increasing from 0.95 to 1.02,initial permeability does not change obviously.2.The effects of preparation technologies on Ba₃Zn_1.2Co_0.8Fe₂₄O₄₁ hexaferrites. Time t₁ has little effect on permeability of Z-type hexafrrites,when tl is 10h, permittivity is maximum.When calcining temperature is 1200℃,initial permeability is maximum,resistivity is minimum,and the grain structure is plane with less pores.When the rate of calcining increasing temperature is 2℃/min,the permeability is maximum and the reflction loss is mimimum at low frequency;the permeability is maximum when the sintered temperature is 1270℃.3.The effects of addictives on Ba₃Zn_1.2Co_0.8Fe₂₄O₄₁ hexaferrites.When PZT addictive content is 1%initial permeability is maximum,when PZT content is 0.2%the permittivity is maximum,resistivity increases with PZT content increasing.When BST addictive content is 1.5%,initial permeability and permittivity are maximum,and excess BST addictive would make the resistivity increase.With NiCuZn ferrite addictive content increasing,initial permeability decreases and reflection loss increases. Some Bi₂O₃ could increase initial permeability,but excess Bi₂O₃ could decrease permeability.When Bi₂O₃ content is 0.6%,initial permeability is maximum and permittivity is minimum.4.During the frequency 1.8～18GHz,the effects of Zn²⁺ content,PZT addictive, BST addictive and NiCuZn ferrite addictive on the electromagnetic properties of Z-type hexaferrites Ba₃Zn_1.2Co_0.8Fe₂₄O₄₁ are investigated,the results show that Z-type hexaferrite material with reflection loss below -3dB could be obtained.