Research On High-Temperature Superconducting Filters And Duplexer With Suppressive Properties

The demand of modern society for wireless communication technology is increasing,but the spectrum resources are limited,which puts forward higher requirements for the accuracy and anti-interference performance of wireless communication system.Filter is the core device in the wireless communication system.The high-temperature superconducting filter and duplexer with the characteristics of low insertion loss and strong out-of-band rejection have important application value for the future wireless communication system.In this thesis,the low-frequency narrow-band high-temperature superconducting filters with great out-of-band performance,ultra-wideband high-temperature superconducting filter with wide rejection performance and high-frequency high-temperature superconducting diplexers with high isolation,which are the main aspects of filters with suppressive properties at present,are systematically studied.An extremely compact spiral resonator,which line width of external port is increased to improve the electric coupling,is proposed.Two transmission zeros are introduced on both sides of the passband to make the band edge steep degree high with the cascaded sextuplet cross coupling.A VHF band high temperature superconducting narrow-band filter with high steepness of band edge and excellent out-of-band suppression performance is realized.An improved S-type spiral resonator,which can push up spurious modes,is proposed.By taking advantage of its weak parasitic coupling,a narrow-band high-temperature superconducting filter with high out-of-band inhibitory performance is realized in UHF band.The quarter wavelength step impedance resonator which can push up spurious modes and reduce size is proposed.Two coupling modes of quarter wavelength step impedance resonator are analyzed,and a narrow-band HTS filter with wide suppression is designed.With the use of the ground capacitance,the strong coupling of the grounded resonator is realized and an ultra broadband response is achieved.The method of introducing band-stop structure by the split of the first and last section resonator is proposed to suppress the harmonic of the filter.An ultra-wide bandwidth filter with a wide rejection characteristic and a fractional bandwidth of 70% is achieved.A folded U-type resonator with weak non-adjacent coupling is proposed to solve the problem of strong non-adjacent coupling of high-frequency filter.By using the local adjustment method of microstrip line width,the accurate adjustment of high-frequency resonator is realized.According to the analysis of duplexer's configuration and metal packaging box's resonant mode,we propose a T arrangement way which is suitable for high frequency high temperature superconducting duplexer.By avoiding the cross coupling between the two channels,an X-band narrow-band high temperature superconducting duplexer with high isolation is realized.The isolation is greater than 70 d B.