Research Of Overmode Bend Waveguide

High-power microwave technology was a newly developing subject in the 1970's.In a few decades,this subject had rapidly developed and received extensive attention.At the present time,it could be widely used in military,scientific research,industrial processing,making new material and medical science,biology et.With the development of high-power microwave,high-power microwave transmission plays an important role in high-power microwave system. high-power microwave transmission system has increasingly received public attention.The feeder which is applicable to high-power microwave,compared with common feeder,is further required to support high power.Therefore,in the high-power microwave feeding system,we always use waveguide elements with high power capacity,and avoid using medium in the waveguides.Circular waveguide and coaxial waveguide are two commonly used microwave elements.For example,relativistic backward-wave oscillator and tapered slow-wave structure generator et,which use circular waveguide to extract energy,output circular waveguide TM01 mode; Transit management and relativistic klystrode et,which use coaxial waveguide to extract energy,output coaxial TEM mode. The TMoi mode is not the lowest order mode of circular waveguide,so that it must transmit in overmode waveguide,and for coaxial waveguide transmitting TEM mode need improve the power capacity,it generally uses overmode waveguide for transmitting,too.While the modes transmitting in overmode waveguide meet some inhomogeneity,it easily arouses other modes,thereby reducing the their efficiency. Avoiding or reducing the complicated modes generating in turn waveguide,and keeping the consistency of output mode with input mode,are difficulties that need urgently solve,and have important value of research and application.In view of this background,this paper makes theoretical research of overmode bend circular mode waveguide and overmode bend coaxial waveguide,and respectively designs 45°bend overmode bend circular mode waveguide and 45°bend overmode bend coaxial waveguide,then does numerical simulation as well as experimental research.TThe main work of this paper is as follows:1. Analyze the research status of bend waveguide.2. Design and experiment study of overmode bend circular waveguide. Through the theoretical analysis of half-circular waveguide,design an overmode bend circular waveguide. The design principle is as follows:the circular waveguide TM01 mode is converted to half-circular waveguide TE11 mode by inserting fins into the overmode bend circular waveguide along the plane of bend. After transmission by the bend,the half-circular waveguide TE11 mode is re-converted to the circular waveguide TM01 mode. Then do numerical simulation as well. On this basis,we design a coaxial TEM to circular TM01 mode convertor, which make coaxial TEM mode convert to circular waveguide TM01 mode. Do experimental research of overmode bend circular waveguide which is processed accordance with optimal size of machining.3. Design of overmode bend coaxial waveguide.Through the theoretical analysis of 180°fan-shaped waveguide,Design an overmode bend coaxial circular waveguide. The design principle is as follows:the coaxial waveguide TEM mode is converted to fan-shaped waveguide TE11 mode by inserting fins into the overmode bend coaxial waveguide along the plane of bend. After transmission by the bend,the fan-shaped waveguide TE11 mode is re-converted to the coaxial waveguide TEMmode.Then do numerical simulation as well as optimized design of this overmode bend coaxial circular waveguide.4. Optimization design of overmode bend coaxial waveguide. Because of the existence of inner conductor at the overmode bend coaxial waveguide, the difficulty of processing is added. For solving this problem, we do some improvement of overmode bend coaxial waveguide. The method of Using the coaxial transformed into half-circular waveguide, then bend transmission.