Research And Application Of Low Loss YIG Ferrite Material And Its Circulator

Microwave garnet type Y₃Fe₅O₁₂ ferrite（YIG）is an important basic material for microwave ferrite devices（circulators,isolators,etc.）in the development of 5G communication industry.With the development of microwave devices for 5G communication towards miniaturization,lightweight,high frequency and integration,microwave YIG ferrite materials are required to have excellent comprehensive properties such as high saturation magnetization,low dielectric loss and narrow ferromagnetic resonance linewidth,so as to meet the application requirements of circulator and isolator in 5G communication.In this thesis,low loss YIG ferrite materials were prepared by means of solid-state reaction sintering by means of ion doping regulation,and their properties were tested and analyzed to study the effects of different ion doping on the properties of YIG materials.Firstly,a relatively complete YIG ferrite theory and process system are introduced,its crystal structure,magnetic source and ion substitution law are analyzed,and the process parameters such as ball milling time,sintering temperature and granulation are studied and optimized to obtain the stable formula and process.Then,the effects of In³⁺doping,Gd³⁺-In³⁺composite doping,Ca²⁺-In³⁺-Ge⁴⁺composite doping and Ca²⁺-Zr⁴⁺-Ge⁴⁺composite doping on the properties of YIG materials were studied experimentally.The results show that In³⁺,Ca²⁺,Zr⁴⁺and Ge⁴⁺ions can enter the garnet lattice of YIG ferrite,affect the saturation magnetization of the material,and help to reduce the dielectric loss and ferromagnetic resonance linewidth.In the study of In³⁺doping,when the doping amount of In³⁺is 0.45,the maximum saturation magnetization is 1840.3 Gs and the minimum ferromagnetic resonance linewidth is 36.7 Oe.In the study of Ca²⁺-In³⁺-Ge⁴⁺composite doping,when the substitution amount of In³⁺is 0.60 and the substitution amount of Ca²⁺-Ge⁴⁺is 0.40,the YIG ferrite material has very small electromagnetic loss,its dielectric loss is 3.053?10^-4and the ferromagnetic resonance linewidth is only 19.3 Oe.In the study of Ca²⁺-Zr⁴⁺-Ge⁴⁺composite doping,when the substitution amount of Zr⁴⁺is 0.50 and Ca²⁺-Ge⁴⁺is 0.40,the electromagnetic loss of the material is also relatively small,the dielectric loss is 4.143?10^-4 and the ferromagnetic resonance linewidth is 27.8 Oe.And in the study of Gd³⁺-In³⁺composite doping,under the premise that the substitution amount of In³⁺is 0.60,Gd³⁺doping will lead to another phase in the material,and increases the dielectric loss and ferromagnetic resonance linewidth.Therefore,low loss YIG ferrite materials can be prepared by single or composite doping of an appropriate amount of In³⁺,Zr⁴⁺and Ge⁴⁺ions,which has a good application prospect in microwave ferrite devices.Finally,based on the electromagnetic performance parameters of low loss ferrite materials Y_2.6Ca_0.4In_0.6Ge_0.4Fe₄O₁₂ prepared in the experiment,Ansoft HFSS software was used to model,simulate and optimize the circulator.The simulation results show that at the center frequency of 10 GHz,the isolation of the circulator is-20.13 d B,the reflection loss is-20.64 d B,the insertion loss is-0.24 d B,the relative bandwidth is more than 30%,and the maximum voltage standing wave ratio is 1.19,which meets the design requirements of the circulator,reflecting that the ferrite material has excellent neutral performance in the application of the circulator.