Research On Broadband Ridge Waveguide Passive Devices

Traditional passive waveguide devices include TE/TH type power dividers,waveguide magic T's,directional couplers and filters.At present,the development of these devices faces several major limitations:First,due to single-mode transmission requirements,the relative operating bandwidth of many waveguide devices are relatively narrow,resulting in the broadband advantages of high-frequency microwaves not being fully utilized.Secondly,most waveguide devices have three-dimensional structures,and need to be connected by flanges.If multiple waveguide devices are required in the same system,the difficulty of connection will increase.Finally,waveguide devices are mostly rigid devices?flexible waveguides are usually expensive?,and they are difficult to bend and twist during the design and assembly process.The above situation has limited the development of microwave systems to a certain extent.Broadband and miniaturized waveguide devices will become an inevitable demand.The main work in this dissertation is to use the ridge waveguide to widen the working bandwidth of commonly used passive waveguide devices,and at the same time improve their performance from multiple aspects such as planarization,output phase difference,port direction consistency,power capacity and miniaturization.The main body of the thesis is divided into eight chapters.The main innovations can be summarized into the following five aspects:1.A broadband waveguide power divider with inverted output phases is realized.Compared with the traditional power divider,the ports of this structure can achieve equal amplitude with inverted output phases in a wide band,and can be applied to microwave devices with phase inversion requirements such as phased array antennas.It is obtained by rotating the input port of a traditional waveguide T-junction along its axis by 90°.And by adding a multi-level ridge waveguide matcher,a wider operating bandwidth is achieved.2.The quasi-planarization designs of waveguide device are studied.The thesis discusses the problems of waveguide devices and proposes some quasi-planar solutions.The resulting quasi-planar devices include quasi-plane waveguide magic T's,quasi-plane TE₀₁-TE₂₀ mode converters,quasi-plane power dividers with inverted output phases,and so on.These quasi-planar design solutions help miniaturize microwave systems and reduce the impact of processing and assembly errors on performance.3.A new design method of waveguide mode adapter is proposed,and a parallel output broadband waveguide mode adapter is designed.It can suppress the TE₁₀ mode in the output port and achieve 95%TE₀₁-TE₂₀ mode conversion efficiency in a 30%relative bandwidth.It is obtained by symmetrically arranging the structure from left to right,rotating the input port 90°around its axis,and adding a multi-level ridge waveguide matcher to the structure for broadband design.4.A design scheme of dual-channel wide-stopband waveguide harmonic suppressor is proposed.This design effectively increases the power capacity of the capacitor-loaded filter without increasing the external dimensions of the filter.The different effects of T-shaped metal loading on the resonance frequency are discussed first.Then a dual-channel wide-stopband harmonic suppression filter was built in conjunction with the waveguide power divider,and the feasibility of the design was verified.5.A new ridge waveguide coupling scheme is proposed to enhance the coupling between it and the external circuits.The directional coupler designed in this paper uses a spine-hole coupling method.Unlike the way that the traditional four-ridge waveguide directional coupler opens a coupling hole in the non-ridge region,the present method not only maintains the advantages of broadband transmission of the ridge waveguide,but also increases the coupling between the ridge waveguide and other circuits due to the electric field concentrated between the metal ridge and the cover plate,The disadvantage of weak external coupling is to implement a new method to enhance coupling.At the end of the dissertation,the full text is summarized,and the future work is prospected.