Research On The Measurement Technology Of Spin-Wave Resonance Linewidth Of Gyromagnetic Materials

Magnetic materials are widely used in the microwave field.Gyromagnetic material is a type of magnetic materials.Many microwave devices can be made using their gyromagnetism,such as isolators,limiters,circulators and phase shifters,which are widely used in various electronic equipment,such as radar,navigation,communication and telemetry.Spin-wave resonance linewidth is one of the important parameters of gyromagnetic materials,which reflects not only the high-power performance of the material,but also the loss characteristics of the material away from the resonance region.Thus measuring the spin-wave resonance linewidth of gyromagnetic materials is of great significance for the research of gyromagnetic materials and the design of gyromagnetic devices,especially for high-power devices.In this paper,the measurement technology of spin-wave resonance linewidth of gyromagnetic materials is mainly studied.After understanding the research trends of spin-wave resonance linewidth measurement technology at home and abroad,it is determined that the purpose of this study was to provide a test system that can measure higher spin-wave resonance linewidth at lower power.In order to achieve this purpose,the theories related to the spin-wave resonance linewidth test were first analyzed,and based on these theories the test scheme was determined to measure the threshold magnetic field value of spin wave excitation according to the phenomenon of waveform distortion so as to calculate out the spinwave resonance linewidth.Meanwhile,the test device was designed.Then,the essential microwave devices in the test system were developed,including the resonant cavity that can highly efficiently concentrate the microwave magnetic field and adjustable attenuator.The microwave magnetic field in the resonant cavity is highly efficiently concentrated by partially filling the cylindrical cavity with a dielectric.Therefore,a stronger microwave magnetic field can be generated at the center of the resonant cavity with a lower input power so that a higher spin-wave resonance linewidth can be measured.Subsequently,a set of spin-wave resonance linewidth test system composed of signal source,adjustable attenuator,pulse power amplifier,bidirectional directional coupler,microwave resonant cavity,detector and oscilloscope was designed and integrated.Finally,some gyromagnetic materials were tested with the integrated spin-wave resonance linewidth test system,the test results were given and the sources of errors were analyzed.Higher spin-wave resonance linewidth can be measured at lower power using the test system developed in this study which is more economical and practical than the existing test systems.