The Research Of Y-type Hexaferrite And Its Application In RF Wideband Devices

As the development of modern communication system,devices should be able to work in high frequency and broadband.In order to meet these requirements,better soft ferrites are urgently needed.In this condition,Y-type barium ferrite is an ideal high frequency soft magnetic material for its high natural resonant frequency and good electromagnetic performance.Compared to other hexagonal ferrites,the features of Y-type barium ferrite are simple structure,easy preparation,and high frequency stability,and its theoretical cutoff frequency is above 5GHz.In this paper,broadband RF device is designed based on electromagnetic property of pure Co₂ Y and ion doping.In this paper,the experiment adopted solid state reaction.Contrasting the properties of different sintering temperature and heating rate,the overall performance was optimal when sintering temperature was 1175? and the heating rate was 1?/min.The formula of Ba2Co₂CuxFe12O22 was used to analysis the different properties and sintering temperature of Co₂ Y caused by changing amount of CuO.Because of the existence of CuO,the grains got good growth in 1100?.CuO could lower sintering temperature and facilitate the uniformity of structure and composition.The loss of magnetic anisotropy and decline of saturation magnetization led to the increase of ?i.Then,by comparing different pre-sintering temperature of Cu2 Y,better pre-sintering temperature was 1000?.Dense material was prepared and 4?Ms=1848Gs.The increase of Hc was possibly caused by synchronous influences of magnetic anisotropy and saturation magnetization.As Zn²⁺ ion is non-magnetic,and it occupies the sub-latice without changing the spin direction,ZnO doping can improve the net magnetic moment of material.By using co-doping of CuO and ZnO,samples with,?'=9.2,?''=0.6,fr=2GHz were got when sintered under 1125?.At the same time,the increasing of Fe²⁺ led to the decrease of ?',which will increase electromagnetic loss in high frequency.Iron-deficiency formula can reduce the eddy current in high frequency.When iron deficiency was 0.04,?'=9.6,?' =0.6,Q=16.7,?'=18,and electromagnetic loss was low.We could get high permeability and low loss material by this way.Finally,the Co₂ Y prepared by experiment was used to design power combiner/divider.Based on the theory of transmission line transformer,the isolation,transmission and other parameters were calculated through the analysis and calculation of circuit.A circuit based on a good matching and isolation structure was designed.The design requirement of device was insertion loss?0.6dB,voltage standing wave coefficient<1.4,isolation degree?-20 dB when used from 50 MHz to 300 MHz.According the requirement,structure of the power combiner/divider and matching circuit were designed.A power combiner/divider was made according to the design and analyzed with a vector network analyzer.In the range of 50MHz-200 MHz the power combiner/divider can initially achieve its function.