Research On Low Temperature Sintering Of LiZnTi Ferrite And Application Of X-Band Phase Shifter

With the development of phased array radar system towards to be miniaturized,integrated and high frequency,as the core component of phased array radar system,the performance and volume of phase shifter have become the key factors that restrict the development.In recent years,the emergence of low temperature co-firing ferrite?LTCF?technology has provided an effective solution to reduce the volume of ferrite phase shifters.However,as one of the excellent gyromagnetic magnetic materials for making ferrite phase shifters,the microwave loss characteristics?ferromagnetic resonance linewidth and dielectric loss?of LiZn ferrite will increase sharply when it is applied to LTCF technology and co-firing with silver electrodes at low temperatures?⁹00 ??,which will lead to the loss of ferrite phase shifters increase and deteriorate the performance of phased array radar system.Therefore,this paper studies the characteristics of low temperature sintering?⁹00 ??and low microwave loss of LiZn ferrite and its application in X-band ferrite phase shifter.Firstly,based on the Bi-substituted LiZnTi ferrite formulation,the influence of BZB glass doping on the microstructure and gyromagnetic properties of the material was studied.The results show that the incorporation of BZB glass can effectively reduce the sintering temperature.For samples sintered at 900?,the coercivity can be as low as240.8A/m and the ferromagnetic resonance linewidth can be as low as 220Oe.Next,the effects of V-Bi composite substitution on the microstructure,gyromagnetic properties and dielectric properties of LiZnTi ferrite materials were investigated.The results show that the low melting point ions V⁵⁺and Bi³⁺can reduce the activation energy of the lattice,promote the growth of crystal grains andincrease the sintering density of the material.The optimal properties of the material are as follws:the remanence ratio is 0.87,the saturation magnetization 4?Ms is 4451Gs,the coercive force is 235.7A/m,and the ferromagnetic resonance line width is 168 Oe,and the dielectric loss tangent is 7.75×10^-4.Then,the LiZn gyromagnetic material which is suitable for LTCF technology and has good gyromagnetic properties and low loss characteristics is obtained by Li-Bi composite substitution method.When the sintering temperature is 900? and the substitution amount of Li-Bi is 0.01,the properties of the material are as follws:the remanence ratio is 0.89,the saturation magnetization is 4?Ms is 4335Gs,the coercive force is 209.5A/m,ferromagnetic resonance line width is 159Oe,dielectric loss tangent is 2.92×10^-4.Finally,based on the theory of transmission line and the working principle of ferrite phase shifter,the X-band ferrite phase shifter with microstrip line structure was designed and simulated by HFSS15.0 software.And then the X-band ferrite phase shifter which used LiZn gyromagnetic material with the best performance as the substrate material of the phase shifter was fabricated by LTCF process.The test results show that at the center frequency 9.3GHz,the insertion loss of ferrite phase shifter is 2.65dB,the return loss is 12.36dB,and the maximum phase shift is 280.6 degrees.