Design And Research Of Band-stop Filter Based On YIG Single Crystal Film

In the field of wireless communication,tunable band stop filters are widely used in achieving miniaturization of the entire machine,resolving channel congestion,and suppressing signal interference.Among them,tunable broadband microwave devices such as band stop filters designed based on yttrium iron garnet(YIG)are indispensable in military applications and long-distance communications,such as the ability to flexibly and rapidly intercept enemy interference signals in electronic warfare,and promote the miniaturization of the entire machine in civil communications.Thesis describes the development status of YIG band stop filters at home and abroad,the parameters of YIG ferrite materials,and the corresponding relationship between them and device parameters.Aiming at the problems faced by YIG ball band stop filters,such as low yield of YIG ball resonator,complex cavity structure,and inconvenient integration,thesis focuses on the research of YIG thin film band stop filter technology,starting from the design theory of YIG band stop filters,Based on the ferromagnetic resonance principle of YIG ferrite and the filter synthesis theory,three different frequency band YIG single crystal thin film band stop filters have been developed in four aspects: wide tuning range,high suppression depth,wide stopband,and planarization for easy integration:1、Using the coupling between a third order YIG thin film resonator and a step impedance low-pass filter,a C band tunable YIG band stop filter has been developed.The filter structure has been processed and measured.The 3 d B bandwidth in the full frequency band is greater than 70 MHz,and the maximum stopband rejection is about-40 d B.The filter has a compact structure,low cost,and is planar and easy to integrate.2、Aiming at the two issues of suppression and tunable range of YIG band stop filters,a high suppression band stop filter based on YIG single crystal thin film with a wide tuning range was developed by coupling a ninth-order YIG thin film resonator with a pair of cascaded deformed quarter impedance converters.The filter structure was processed and measured,and the filter was adjustable in 5-20 GHz,with a 3 d B bandwidth greater than 140 MHz in the full frequency band,The maximum stop band suppression system is about-80 d B.3、 Aiming at the problem of the band stop width of YIG band stop filters,a wide stopband band stop filter based on YIG single crystal thin film was designed by using YIG thin film as a microstrip circuit substrate and coupling high impedance multi branch microstrip lines with YIG thin film.The structure was modeled and simulated,and simulation results were obtained that were consistent with theory.The filter was adjustable within 10-20 GHz,with a 3 d B bandwidth greater than 2 GHz in the full frequency band,the maximum stop band suppression system is about-65 d B.Finally,thesis makes a prospect for the development of YIG band stop filters.The design of various YIG band stop filters in thesis provides a reference basis for the design of YIG thin film band stop filters.