Study Of Compact Circular Waveguide Transmission Line With High Efficiency

High power microwave technology is one of research hot fields in the world at present, which has a wide range of applications in the many aspects such as military, civilian, scientific research. Transmission system is a key part of the system, which decides the performance of high power microwave system and determines the efficiency of transmission and use of microwave energy. Moreover, circular waveguide transmission line(such as the mode converter and transition) is the essential device in the transmission system, Therefore, study of compact circular waveguide transmission line with high efficiency is vital important for improving the performance of the whole system, and promoting the development of high power microwave technology.In this dissertation, theoretical and experimental studies of the design on circular waveguide transmission line(the mode converter and transition) are implemented based on the coupled wave theory, iterative synthetic method, the non-uniform rational B-spline(NURBS) technique and other key technologies.The mainly work and study results are given below:1. Iterative synthetic method, who is the advanced design method of circular waveguide devices at present, was studied based on the coupled wave theory. Numerical calculation codes of iterative synthetic method of bending circular waveguide are written to analyze and optimize the TM01-HE11 mode converter and the 90-degree waveguide bend for TE01 mode transmission. Calculations indicate that iterative synthetic method can design compact circular waveguide devices with high efficiency. Moreover, the disadvantages of the iterative design are discovered and given.2. A method for synthesis of circular waveguide mode converter and transition is proposed based on the coupled wave theory and the NURBS technique in order to make up for the disadvantages of the iterative design. Codes to analyze and optimize them are written. By the codes, a highly fair 90-degree bend for TE01 transmission and a TE01-TE11 mode converter which has coaxial-parallel input and output ports are developed. Experiments show agreements with the calculations.3. The method for synthesis of TM11- HE11 mode converter with compact and high efficiency is put forward based on the NURBS technique and the technique of MATLAB calling the commercial software Microwave Studio CST in order to make up for the disadvantages of the traditional design method. Codes to analyze and optimize them are written. This converter is designed by the optimal structure parameters. The hot test indicates the converter has a good property of HE11 mode conversion from TM11 mode. Experiments show agreements with the calculations.