The Research Of High Performance Gyromagnetic Ferrite Materials And Their Applications

As the basic material of modern electronic information industry, microwave ferrites are widely used in military radar and commercial wireless communications. Because of its excellent performance, garnet ferrite, as a common microwave ferrite, is widely used and researched. YIG which is a typical garnet ferrite has low dielectric and magnetic loss and excellent temperature stability. YIG is widely used in microwave device such as circulator and isolator. This paper mainly focused on how to reduce the dielectric and magnetic loss of pure YIG and designing circulator based on low loss YIG.Firstly, crystal structure, magnetic source and the rule of ion substitution of garnet ferrite were studied which provided theoretical support for changing performance by adulteration. Secondly, the preparation processing of oxide method and analyzing means of material were introduced and the most appropriate sintering temperature was confirmed. Analysis results indicated that when sintered in 1450℃, sample of pure YIG had best microtopography and electromagnetic performance. Thirdly, the most important research was how to reduce the dielectric and magnetic loss of YIG. The dielectric loss was reduced by decreasing iron content and adulterating Mn2+. Analysis results indicated that the dielectric loss was reduced obviously and other electromagnetic performance behaving well when x=0.18 for Y3Fe5-x O12 and x=0.15 for Y3Fe5-3xMn2 xVx O12. The magnetic loss was reduced by adulterating Sn4+. Analysis results indicated that the magnetic loss was reduced obviously and other electromagnetic performance behaving well when x=0.4 for Y3-xCax Fe5-xSnxO12. The dielectric loss and magnetic loss were reduced together by adulterating Mn2+ and Sn4+ jointly. Analysis results indicated that the dielectric and magnetic loss was reduced obviously and other electromagnetic performance behaving well when x=0.2 for Y3Fe5-2xMnxSnx O12 which proved that co-doping was effectively.Circulator was designed based on low loss YIG. The size of circulator was confirmed by the first and the second circuit conditions. Then the 3d model of circulator was established and optimized by HFSS. The simulation result indicated that the circulator which was designed base on low loss YIG was complied with the design requirement in X band: insertion loss less than 0.5dB, return loss and isolation greater than 18 dB. Then the circulator was produced by silk screen printing and tested by vector network analyzer.