A Research On The Gyromagnetic Properties And Application Of NiCuZn Ferrite

The rapid development of passive phased radar systems means higher requirements on the performance and miniaturization of its core components,ferrite phase shifters.As the core device of the system,the ferrite phase shifter has become a research hotspot because of its excellent performance and miniaturization.As the key material of the ferrite phase shifter,NiCuZn ferrite has low ferromagnetic resonance line width??H?,low coercive force?H_c?,and high magnetic induction?B_s?and high density?D?.However,When fabricating ferrite phase shifter based on LTCC technology,the problem of matching co-firing between ferrite substrate and wire paste becomes particularly prominent factor.This is mainly due to the deterioration of the?H property and the dielectric loss performance of the ferrite material,which leads to the deterioration of the bad performance of the ferrite phase shifter.Consenquently,in order to achieve the low insertion loss,low return loss,high performance stability and small weight of ferrite phase shifters,NiCuZn substrate materials should possess excellent gyromagnetic properties on the basis of low temperature sintering.This academic paper's thesis is mainly based on the optimization of the gyromagnetic properties of NiCuZn ferrites and its application examples in X-band ferrite phase shifters.Firstly,built on the iron-deficient formula(Ni_0.2Cu_0.2Zn_0.6O)_1.03?Fe₂O₃?_0.97,the phase composition,microstructure,gyromagnetic properties of NiCuZn ferrites with BZB glass addition were systematically studied.The results showed that BZB glass significantly improved the density,gyromagnetic properties and low-temperature sinterability through the liquid phase sintering mechanism.Then,considering the possibility of microstructure optimization,a sintering system of BZB+MoO₃ with a certain melting temperature range was designed.The results showed that the average grain size and compactness of the structure were improved by a small margin,meanwhile the gyromagnetic properties were further optimized.Finally,based on shortening the temperature range for grain growth by reducing the melting temperature range of the sintering system of glass and oxides,BZB+V₂O₅ system was designed.Finally,we prepared a microstructure with multiple grains with a large increase in the average grain size,meanwhile the gyromagnetic properties were also greatly optimized.And it was found that when the sintering temperature is 870°C,the added amounts of BZB glass and V₂O₅ is 0.15 wt%and 0.60 wt%,respectively,the ferrite material achieved the best comprehensive property??H=¹43.7Oe,4?M_s=⁴836Gs,H_c=⁷5.2A/m,D=⁵.2g/cm³?.Generally speaking,gyromagnetic materials require samples have large average grain size,high grain filling rate,compact and dense microstructure.And a system with glass and low-melting oxide can not only effectively improve gyromagnetic properties,but also optimize the microstructure of the NiCuZn material.Finally,we designed and simulated an X-band ferrite phase shifter with HFSS15.0,based on the transmission line theory and the operating mechanism of the phase shifte.The self-developed ferrite material was chosed as the substrate material for the ferrite phase shifter.The simulation results showed that in the frequency range of 9.05-9.35GHz and 9.6-9.9 GHz,the insertion loss|S₂₁|is less than 2.5dB.Meanwhile,when the operating frequency is during 10 GHz to 10.9 GHz,the return loss|S₁₁|is less than 10dB.The VSWR value is less than 3 in the frequency range of 9-11 GHz.And at the center frequency of 9.3 GHz,the insertion loss|S₂₁|is 2.49 dB,the return loss|S₁₁|is 8dB,the VSWR value is 2.8,the phase shift is 240°.