微波多晶石榴石-尖晶石铁氧体复合基片制备及其宽带环行器应用仿真设计

Preparation of microwave polycrystalline garnet-spinel ferrite composite substrate and the simulation design of broadband circulator application

采用普通陶瓷工艺制备了微波多晶石榴石和尖晶石铁氧体粉料,分别采用一体成型和分体成型嵌套方式制备了复合生坯。分析了两种成型方式共烧复合基片的微观形貌。一体成型时,内芯尖晶石生坯成型压力是正常成型压力110 MPa的80%~85%时,可有效避免复合基片内芯的微裂现象;分体成型时,分体成型生坯后再嵌套复合后进行等静压致密化,能有效避免两相复合处的微观裂纹、缝隙等缺陷。一体复合较分体复合基片有更好的质量,微观裂纹、缝隙缺陷少,但成型控制难度大,两种成型方式的共烧复合基片均存在两相互扩散过渡区域。并进行了石榴石-尖晶石复合基片与单一石榴石、尖晶石基片在三倍频程6~18 GHz超宽带微带环行器的应用仿真设计,仿真结果表明复合基片能有效拓展器件的带宽、降低插损,较单一基片在宽带环行器设计中更有优势。

Microwave polycrystalline garnet and spinel ferrite powders were prepared by common ceramic process,and composite green bodies were prepared by one-piece forming and separate forming respectively.The composite billet was prepared by integrated composite forming and separate compound nesting.The micro morphology of co-fired composite substrate was analyzed.When the forming pressure of the green spinel with inner core is 80%-85%of the normal forming pressure of 110 MPa,the micro crack phenomenon of the inner core of the composite substrate can be effectively avoided;when the green spinel with inner core is formed separately,the green spinel with inner core is nested and compacted by isostatic pressing,which can effectively avoid the micro crack,gap and other defects at the two-phase composite.The integrated forming composite substrate has better quality than the split forming composite substrate,with fewer micro cracks and crevices,but it is difficult to control the forming process.There are two mutual diffusion transition regions in the co-fired composite substrate of the two molding methods.And the simulation design of garnet-spinel composite substrate and single garnet and spinel substrate in 6 to 18 GHz ultra broadband microstrip circulator is carried out.The simulation results show that the composite substrate can effectively expand the device bandwidth and reduce the insertion loss,and has more advantages than a single substrate in the design of broadband circulator.