Research Of Low Temperature Sintered LiZn Ferrite And LTCF Phase Shifter

With the advent of modern high-tech war era,microwave technology and space technology have become the key development technologies.The excellent performance of phased array radar in real-time monitoring,fixed-point interception and other aspects has attracted people’s attention.Ferrite phase shifter is an important component of phased array radar.As an excellent device material,LiZn ferrite is often used in the preparation of ferrite phase shifter.In order to improve the performance of the ferrite phase shifter and adapt to the development of its miniaturization and integration,low-temperature co-fired ceramic（LTCC）technology is proposed.However,when LiZn ferrite is sintered below the melting point temperature of Ag（<960℃）,the material has more pores and the density becomes worse,and it cannot be well applied to ferrite phase shifters.Therefore,many scholars continue to study and want to prepare materials with high density and good gyromagnetic properties that can be applied to technology.This dissertation mainly studies the influence of three additives,V₂O₅-Al₂O₃,V₂O₅-Bi₂O₃,Bi₂O₃-NiO,on LiZn ferrite materials.By doping with complex oxide additives,LiZn ferrite materials with a sintering temperature of less than 960℃ are obtained.The experimental results show that proper amount of composite oxide doping can improve the compactness,increase the gyromagnetic properties and reduce the sintering temperature.At 950℃ sintering temperature,the saturated magnetic induction intensity of the sample doped with 0.18 wt%V₂O₅-0.18 wt%Al₂O₃ is 286 m T,the coercoerity is 209 A/m,and the ferromagnetic resonance linewidth is 253 Oe.The saturated magnetic induction intensity of LiZn ferrite doped with 0.12 wt%Bi₂O₃-0.06 wt%V₂O₅（Bi₂O₃:V₂O₅=2:1）is 321 m T,the coercivity is 149 A/m,and the linewidth of ferromagnetic resonance is 264Oe.The saturated magnetic induction intensity of LiZn ferrite doped with 0.25 wt%Bi₂O₃-0.15 wt%NiO（x Bi₂O₃-y NiO,where x+y=0.4 wt%）is 334 m T,the coercivity is130 A/m,and the linewidth of ferromagnetic resonance is 177 Oe.This article attempts to design a stripline phase shifter using HFSS 15.0 software simulation.The results obtained after simulation and optimization are as follows:at around 30 GHz operating band,the stripline phase shifter achieves a differential phase shift value of about 330°,the absolute value of insertion loss is about 0.9 dB,the absolute value of return loss is about 21 dB,and the voltage stands wave ratio is about 1.1.The performance parameters obtained by simulation reach the design expectation.