Ферритовые резонаторы для приборов миллиметрового диапазона длин волн

Abstract

Currently on the way are R&D works targeted to expand operational frequencies of microwave devices, including frequency selective ones. The expansion occurs both at low and at high end of the frequency range. Due to the microwave communication systems trend of increasing transmitted data flow rate and volume, as well as for precise object resolution by the vision systems, one needs to shift microwave device operational frequencies to the mm-wave range.
 Operational frequencies of mm-wave range microwave devices are defined by crystallographic magnetic anisotropy field and magnetic activity of the ferrite material (4πМS/ΔH), related with saturation magnetization and ferromagnetic resonance (FMR) line width. For creation of mm-wave range frequency selective devices are needed the ferrite resonators made of materials with high crystallographic magnetic anisotropy field values, as well as high saturation magnetization and narrow FMR line width. R&D works undertaken in the institute show that such materials can be created on the basis of ferrites with hexagonal structure. As a starting point for the development of the material was taken barium hexaferrite with M-type structure 
 (BaFe12O19). Single crystals with composition BaFe12-xAlxO19 and BaFe12-xScxO19 were received from a solution in melt. By this way one may create materials with anisotropy field values from 5 to 50 kÖe, saturation magnetization from 3900 to 4700 Gauss, narrow FMR line width, and Curie temperature from 370° to 445° С.
 The dependencies of crystallographic magnetic anisotropy field and saturation magnetization vs diamagnetic dilution and temperature are investigated, as well as FMR line width vs temperature, density and orientation of the growing grains.