Research Of Low Loss LiZn Material With Gyromagnetic And High-remanence Properties And Its Application

Microwave ferrite materials are important basis for microwave ferrite devices that make up military radars and civilian wireless communication devices.Because of low ferromagnetic resonance linewidth,low coercivity,high squareness ratio,high saturation magnetization and high temperature stability,LiZn ferrite materials are widely used in high frequency,high power microwave ferrite devices.In this paper,the conventional solid phase sintering method was used to prepare LiZn ferrites at different sintering temperatures,and Li_0.37+0.5xZn_0.26Ti_xFe_2.37-1.5xO₄ was used as a formula.The substitution rule of non-magnetic ions Ti⁴⁺was used to investigate the incorporation of Ti⁴⁺and the effect of sintering temperature on the magnetic properties of LiZn ferrite.When the sintering temperature is 930°C,an appropriate amount of Ti⁴⁺is added so that the saturation magnetization of the ferrite is reduced to 2400 Gs,and the magnetocrystalline anisotropy constant of the ferrite is lowered.The resonance linewidth contributed by the magnetocrystalline anisotropy field also decreases as the magnetocrystalline anisotropy constant decreases.Since the saturation magnetization interacts with the magnetocrystalline anisotropy field,the coercivity of the material also decreases due to the incorporation of Ti⁴⁺.Subsequent increase in sintering temperature significantly improved the microstructure of the material.When the Ti⁴⁺doping amount was 0.12 and the sintering temperature was 1050°C,the ferromagnetic resonance line width of the material measured at 15.87 GHz was 280 Oe,and the squareness ratio was0.82.Subsequently,LiZn ferrite was simultaneously doped with TiO₂,Mn₃O₄ and sintered at different temperatures.Utilized the Mn₃O₄ to assist the LiZn ferrite combustion characteristics and Mn³⁺’s oxidation characteristics to investigate the incorporation of Mn and sintering temperature’s impact of LiZn ferrite’s performance of dielectric.When samples were sintered at 1000°C and the amount of Mn was 0.08,the relative dielectric constantεγ=15 and the dielectric loss tangent tanδε=0.001 were obtained.The high frequency band and low loss gyromagnetic material required for this experiment were obtained.Based on the experimental parameters of LiZn ferrite,a Ku-band microwave ferrite switch was designed.According to the theoretical calculation of the rectangular waveguide transmission theory,the parameters of the ferrite switch are optimized by HFSS.The simulation results show that the low-loss gyromagnetic LiZn ferrite is used as the microwave ferrite switch of the gyromagnetic sheet.In the frequency range of12.7GHz to 14.7GHz,the switching function of microwave signal can be realized,the return loss of each port is around-15dB and the insertion loss is about-0.2dB,which satisfies the design requirements.