The Research Of Y-type Hexagonal Ferrites And Its Application In The Circulators

Microwave ferrite circulator is widely used in wireless transceivers，which is onekind of important microwave ferrite devices. The circulators mading in traditional spineland garnet ferrite materials are mainly used in the microwave band, and need a strongapplied bias magnetic field. So it is not conducive to the development of the devices ofminiaturization，integration and high-frequency. With high magnetic anisotropy field，hexagonal ferrite materials can be applied to the millimeter wave band. And the appliedbias field required is very small，even without needing external bias magnetic field.Thus，this kind of devices have self-biased function. Y-type hexagonal ferrite materialhas a high plane anisotropy field，which can be made self-biased ferrite coupledmicrostrip line circulators. So it is conducive to the development of devices ofminiaturization, integration and high-frequency.In the part of material experiments，this paper mainly studied the Y-type bariumferrite materials. The low-loss Y-type barium ferrite materials were prepared bytraditional solid-state reaction, and ion substitution was studied. Firstly，Co2Ymaterials were prepared，and the preliminary exploration of the Y-type barium ferrite ofsuitable sintering interval was made，which lay the foundation for the preparation oflow-loss ferrite materials of pure Y phase. In order to prepare the pure Y phase ferritematerials of high densification，Co²⁺was substituted byCu²⁺，and the relationshipbetween the different substitution and the densification of materials was studied.Meanwhile, since the substitution reduced the magnetic anisotropy，the ferromagneticresonance linewidth H was reduced. Ferromagnetic resonance linewidth is directlyrelated to the magnetic loss. Then，when the substitution ofCu²⁺is0.8，the sinteringmethod of densification was studied. Eventually，the highest density ferrite materialswere obtained when they were calcined at1050℃and sintered at1125℃，and therelative density was97.2%. In order to obtain much higher density samples， themethods of iron deficiency formulations were adopted. The formulaBa₂Co_1.2 Cu_0.8 Fe_12-xO_22-1.5(（x=0.04）was appropriate to gain highest density samples.When the samples sintering in oxygen atmosphere，better sintered samples were obtained. The relative density reach to98.3%，and dielectric loss was reduced by oneorder of magnitude. Finally，the studies of theCu²⁺、Zn²⁺substitution forCo²⁺andZn-Ti substitution forFe3+were made，and the properties of materials were studied.In the part of the device，the operating principle of the ferrite coupled line （FCL）circulators had been analyzed. And two kinds of ferrite coupled line circulators hadbeen designed in the use of YIG material and Y-type barium ferrite material respectively.The circulators’ substrates were all the whole ferrite substrates，which could reduce thesize and loss of the FCL circulators. The HFSS electromagnetic simulation softwaredesign results showed that，the circulator based on the YIG materials got lower than3dBinsertion loss，higher than15dB return loss and isolation loss in the frequency range of5.75⁶.25GHz；the circulator based on the Y-type barium ferrite material got lower than4dB insertion loss，higher than10dB return loss and isolation loss with lower than15dBin the frequency range of40.6⁴3.2GHz. Finally, the circulators based on the Y-typehexagonal ferrite materials were made up.