Coaxial Circular Waveguide Tm <sub> 01 </ Sub>-te <sub> 11 </ Sub> Mode Converter Research

High Power Microwave(HPM) is one of the most important fields of microwave technology.People have been doing research on mode conversion and mode control device,which are vital sub-flieds of HPM.Most of HPM source devices,such as Virtual Cathode Oscillator(VCO),Relativistic Backward Wave Oscillator(RBWO) and Magnetically Insulated Transmission Line Oscillator(MILO) operate at symmetric modes,such as TM_0n.Unfortunately,the symmetrical electromagnetism modes TM_0n are not suitable for faraway transmission,mode conversion is necessary for these kinds of high power devices.Coaxial waveguide TM₀₁-TE₁₁ mode converter for C waveband,whose power capacity reaches GW or higher,was successfully designed with the method of dielectric loading.The main works,including design and feasibility of the converter,research on the relationship between length of dielectric and bandwidth,and experiment of the TM₀₁-TE₁₁ mode converter in lab are carried out.The main work is following:1,The fact that discontinuous waveguides create different boundary conditions and finally get different electromagnetism modes is the ground of mode conversion.A physical model of TM₀₁-TE₁₁ mode coaxial conversion with dielectric loading is described and analyzed in the paper.2,The relationship between characteristics of dielectric material and the length and bandwidth of the converter is studied theoretically.The results show that the higher of dielectric constant,the shorter length and the narrower bandwidth of the converter. CST simulation research on the relationship between length of dielectric and working bandwidth is performed and the results agree well with theoretical results.3,Parameters of the mode converter are simulated and optimized with CST for a higher conversion efficiency and wider bandwidth.And then power capacity is estimated on the base of CST data.4,The experiment of the mode converter is performed with Network Analyzer for a theoretical and simulative validity.We use a coaxial line probe to excite TM₀₁ mode in circular waveguide.The TM₀₁ excitation of the coaxial line probe-to-circular waveguide is rigorously treated using the conservation of complex power technique(CCPT).The S₁₁ results detected by Network Analyzer agree well with that of simulation.