Study On Electromagnetic Characteristics Of P-Band NiZn Ferrite Absorbing Materials

With the continuous development of radar detection,it becomes more and more important to study the P band early-warning radar with detection of ultra long range,and the P band electromagnetic absorption materials have attracted much attention.Ni-Zn ferrite composite material has the advantage of high electromagnetic loss,strong corrosion resistance and easy fabrication in the P band.Therefore,the composite of Ni-Zn ferrite with high electromagnetic loss can be prepared to achieve high electromagnetic absorption performance in the P band.In this paper,the purpose of this study was to improve the electromagnetic loss in the P band through using the Ni-Zn ferrite absorbent and its composites.The effects of the formulation and preparation process on the electromagnetic properties of Ni-Zn ferrite absorbent and composites were systematically studied.At the same time,the impact of the thickness of the absorption materials on the electromagnetic absorption properties was also studied.Meanwhile,we added ferrous powders to Ni-Zn ferrite to change the electromagnetic parameters of the composites.The impedance matching of the composites was improved and the absorption property of the composite was increased.The following conclusions were obtained:Considering the electromagnetic properties of ferrite materials,in order to prepare Ni-Zn ferrite composites with high electromagnetic loss in the P band,the content of ZnO should be controlled around 30.6mol%.And the CuO could promote the growth of grains and contributed to the cementation in the master recipe.With the increase of the content of Cu2+,the magnetic permeability increased first and then dropped,and the content of CuO in 7.65mol%could better give consideration to the magnetic properties and cementation characteristics.The content of Fe2O3was controlled about 49.5mol%in the main formulation,which was more conducive to achieve the goal of high loss of Ni-Zn ferrite composites.The changes of prefiring temperature and sintering temperature had great impacts on the real and virtual parts of the magnetic permeability of Ni-Zn ferrite composite material.In order to improve the electromagnetic loss of Ni-Zn ferrite composite material,it is suitable for prefiring temperature to be set at 1000?,and it is appropriate for sintering temperature to be set at 1150?.The change of the secondary ball milling time had great influence on the real and imaginary parts of the magnetic permeability of Ni-Zn ferrite composite material.In order to make Ni-Zn ferrite composite material have high electromagnetic loss,it is suitable for secondary ball milling time to be set for 2.5h.Zn0.612Ni0.255Cu0.153O(Fe2O3)o.99 was used as the main formula,the prefiring temperature was set at 1000?,the sintering temperature was set at 1150?,and the secondary ball milling time was set for 2.5h.The absorbent prepared by the above formula and process and paraffin were mixed with the mass ratio of 9:1.And the Ni-Zn ferrite composite material with a maximum imaginary part of magnetic permeability greater than 6 and a maximum value of 10 in the P band could be obtained.After the plane wave reflectivity calculation.By adding ferrous powder with mass fraction of 10%to Ni-Zn ferrite,the electromagnetic parameters of the composite could be changed,the impedance matching of the composite material was improved,the absorption effect of the electromagnetic wave was enhanced,and the minimum reflection loss with RL<-24dB was reached,and the reflectivity of absorption material can be lower than-10dB in 350MHz-1GHz.