Design And Realization Of Microwave And Millimeter Wave Waveguide Cavity Passive Circuit

With the development of electronic science and technology,as the most basic component of microwave millimeter wave system,the application of microwave passive millimeter wave devices and circuits is becoming more and more important.The passive circuits of microwave millimeter wave system include mode converter,power divider,filter and multiplexer.In recent years,many scholars at home and abroad have studied it deeply.In this thesis,several waveguide mode converters,power dividers and multiplexers with good circuit performance are studied from the microwave millimeter wave waveguide cavity passive circuit.The main research work is as follows:1.Based on the principle of waveguide mode conversion,four waveguide mode converters are proposed to realize the conversion from rectangular waveguide TE10 mode to circular waveguide TM01 mode and rectangular waveguide TE10 mode to over-mode coaxial TEM mode respectively.Then,based on the substrate integrated waveguide(SIW)structure,a microwave power synthesis circuit is proposed.Firstly,an eight-way power splitter circuit is proposed based on the substrate integrated waveguide(SIW)and the waveguide mode converter.The upper part is divided into a coaxial input port,and the lower part is divided into an eight-way power splitter structure from coaxial to SIW.The coaxial step impedance converter is used to match the coaxial and SIW,and finally the microwave power synthesis circuit is realized.2.A coaxial cavity quintuplex is developed.Firstly,five coaxial cavity bandpass filters are designed according to the design index.All the filters are three-cavity cascaded direct coupling mode.By connecting the coupling rod between the cavity conductors,the coupling degree is strengthened to achieve a wide passband.Then,five band-pass filters are connected by a common cavity structure to realize a coaxial cavity quintuplex circuit.3.An ultra-wideband millimeter wave diplexer based on suspended band line structure and waveguide structure is studied.The low-pass filter is implemented with suspended band line structure,and the high-pass filter is implemented with waveguide structure.Finally,the ultra-wideband millimeter wave diplexer circuit is realized by integrating them with suspended microstrip to waveguide transition structure.