Application Research Of Magnetic-dielectric Properties Of Bandwidth Ferrite Materials

With the development of microwave communication,the demand for high frequency,integration and high performance of microwave devices attracted increasing attention.Ferrite materials,as the basic materials for microwave devices,have always been the focus of application and research.Hence,this work mainly is aim at the requirements of microwave plane spiral inductance,microwave circulator and micro-band antenna.The applied requirement of microwave devices and research of magnetic materials were studied.The mainly aim was to broaden the frequency of material and devices,and design and simulate the performance of microwave devices according to the basic materials,to realize the broadband requirements of devices.Firstly,based on the good magnetic properties of MgCd ferrite material,In³⁺ion was chose to substitute the Fe³⁺ion in MgCd ferrite,the chemical formula was Mg_0.8Cd_0.2Fe_2-xIn_xO₄(x=0.00,0.05,0.15,0.10,0.15).By adding different amounts of In³⁺ions,the In-substituted MgCd ferrites were synthesized at 1150? and 1200?.the phase formation was better at 1200? than sample at 1150?,and there were few second phase at high substituting contents(x=0.10 and x=0.15).Meanwhile,when x=0.15,the sample at1200? had high densification and the bulk density was 4.89 g/cm³.For magnetic properties,the saturation magnetization Ms and coercivity Hc changed with different x.when x=0.10,the Ms of 1150? sample is 40.07 emu/g and the Hc=97.15 Oe.when x=0.10,the Ms of 1200? sample is 39.59 emu/g and the Hc=96.16 Oe.It showed that the In³⁺substitution changed the magnetic moment of materials and effected the magnetic properties.Moreover,the In³⁺substituted MgCd ferrite materials were low temperature sintered at 925? with adding 3wt%Bi₂O₃ aids.The results showed that the grain size was more unform,and most of the grain size was between 1.5?m and 3.5?m when x=0.05and 0.10.About magnetic property,when x from 0.00 to 0.10,the saturation magnetization Ms increased from 30.84 emu/g to 33.20 emu/g,while the coercivity Hc decreased from 53.9 Oe to 21.99 Oe.With x reached 0.15,the Ms was 29.44 emu/g and Hc increased to 52.99 Oe.The ferromagnetic resonance line-width(?H)test showed that the value of?H decreased with x increasing from 0.00 to 0.10,and then increased when x=0.15.The minimum value of?H was 219.7 Oe at x=0.10.The research showed In³⁺substituted MgCd ferrite material could be applied on the application of microwave circulator.Secondly,based on the application of planar helical inductors,the chemical formulation and low temperature sintering of NiCuZn ferrite were investigated.The effects of Ni²⁺ion content on phase formation and properties of Ni_xCu_0.48-xZn_0.52Fe₂O₄ferrite were studied.When x changed from 0.22 to 0.28,the phase of samples was spinel phase,but the grain size was affected by Ni²⁺ions.The increase of Ni²⁺content limited the grain growth,and when x=0.26,the great mass of grain sizes were below 5?m and uniform.About magnetic property,when x=0.26,the saturation magnetization of sample was 50.4 emu/g,and coercivity Hc=8.4 Oe,while the magnetic permeability reached the maximum value(?'=180).Based on the Ni²⁺ion content,the Ni_0.26Cu_0.22Zn_0.52Fe₂O₄ferrite were prepared at low temperature(860? and 880?)with different Bi₂O₃ aids.At low temperature,XRD showed there was only spinel phase of NiCuZn at low Bi₂O₃aids.With Bi₂O₃ increasing,the Bi³⁺ion and Fe³⁺ion synthetized the Bi₂₅Fe O₃₉ dielectric phase,which could adjust the dielectric properties of materials.With Bi₂O₃ aids increasing from 1wt%to 5wt%,the magnetic permeability?'showed increase trend,when x=5wt%,?'?100 at 860? and?'?128 at 880?.moreover,?'showed decrease trend with Bi₂O₃ aid further increasing.For dielectric properties,NiCuZn ferrite had a value of?'=10-13 at low Bi₂O₃ aids(1wt%-5wt%).The?'reached a maximum value of14.5 when Bi₂O₃ was 9wt%.The good magnetic and dielectric properties made these ferrites promising candidates for planar helical antenna.Thirdly,the low temperature sintering and magnetic-dielectric property of barium ferrite were studied based on the application of the micro-band antenna.Co₂Z ferrites were synthesized with 27%Bi₂O₃-35%H₃BO₃-6%Si O₂-32%Cu O(BBSC)aids.When BBSC content was 3wt%,the grain of ferrite grew fully and the densification increased,bulk density was 4.655 g/cm³.Meanwhile,the saturation magnetization Ms was 49.6emu/g and coercivity Hc was 163.6 Oe,and magnetic permeability?'reached maximum value 7.3,but the?'value was not suitable to adjusting the magnetic-dielectric effect.Hence,Ba(Co Ti)_1.22Fe_9.56O₁₉ ferrites were synthesized and researched with 5wt%-14wt%Bi₂O₃ aids.Superfluous Bi³⁺ion and Fe³⁺ion formed BiFeO₃dielectric phase,which could adjust the magnetic and dielectric properties.The results showed when Bi₂O₃ was5wt%,the Ms of samples was 33.99 emu/g,and Hc was 59.05 Oe(minimum value).Meanwhile,samples had good magnetic dielectric properties at a range frequency of 1MHz-300 MHz.when Bi₂O₃ was 5wt%,the value of?'was about 18.3,and the value of?'was about 18.1,and magnetic loss tan?_?was about 3.4×10^-2,the dielectric loss tan?_?was about 2.8×10^-3.This materials could be applied in the micro-band antenna.Finally,planar spiral inductors,circulators,and micro-band antenna were designed based on the above materials.Based on the prepared NiCuZn low temperature sintering magnetic mediation material,the inner diameter of planar spiral antenna r₀=1.3 mm,helical width W=1.1 mm,and the helical growth rate a=0.7006.At this time,the S parameter performance of the antenna S₁₁ at frequency point 11.6 GHz is-34.81 d B.The design parameters of the Y-type microwave circulator:central disk junction radius R=2.852 mm,ferrite plate thickness h=0.819 mm.At the central frequency of 9.5 GHz,The reflection loss S₁₁=-18.0561 d B,and the insertion loss S₂₁=-0.5798 d B,and the isolation degree S₃₁=-20.3729 d B.When the frequency is between 7 GHz and 10 GHz,the reflection loss is less than-17 d B,the insertion loss is more than-0.6 d B,and the isolation degree is less than-17 d B,which reached the design requirement.Design parameters of micro-band patch antenna:patch length L=115.5 mm,width W=158.5 mm,resonance frequency f_r=297 MHz,and return loss S₁₁ is less than-14 d B,meeting the design requirements.The design and...