The Reseach On Ka-band Gyro-twt TE₀₁-TM₁₁-HE₁₁ Transmission System

High power millimeter-waves system is composed of high power millimeterwave sources, transmission link subsystem and emission and receiving subsystem. High power millimeter-wave sources subsystem that best choice is gyrotron is the key to the millimeter-wave system, it determines the performance of high power millimeter-wave system. The transmission link subsystem includes mode conversion and transmission device, it makes the millimeter-wave grow out of sources is converted into the wave mode that match emission and receiving subsystem. The emission and receiving subsystem main device is the antenna, it transmit and receive millimeter-wave energy to space.The mode convertor as a part of transmission link subsystem plays an unparalleled important sense to improve the performance of high power millimeter-wave system. Mode conversion can make the energy of high power millimeter-wave source conversion and transmission more efficiently. It has an important function for efficient use of millimeter-wave. Therefore, the study of mode converter has vital significance of research and meaning of engineering application. Funded by the gyrotron pre-research project, this paper has in-depth theoretical study and simulation of the TE01--TM11--HE11 mode conversion sequence. Design and process a new 90-degree curved circular waveguide TE01--TM11 mode converter, numerical results and simulation results have good consistency and used in scientific research experiments successfully. The main work of this paper is below:1. Summarizes the characteristics and all aspects of application of high power millimeter-wave, the development history of millimeter-wave systems and gyrotron, research current situation and development trend of mode converter.2. In-depth study of the coupled wave basic principles, Maxwell equations combined with orthogonal functions expanded theory, deduced coupled wave equations of axis bending circular waveguide mode converter, and which corresponds to coupling coefficient expressions. Detailed analysis the coupled wave equations, and introduce suitable numerical methods for solving the equations and optimization algorithms of parameters.3. With engineering applications, according to coupled wave equations of axis bending circular waveguide and method for solving the equations, this paper write in the optimization procedure to optimize and design a compact, efficient 90-degree bend circular waveguide TE01--TM11 mode converter. The new mode converter on the one hand to achieve turning 90 degree of transmission, on the other hand directly TE01 mode into TM11 mode output. The new mode converter three-dimensional simulation results are consistent with numerical results, and conducted practical, the numerical results show that the design of the 90-degree bend circular waveguide TE01--TM11 mode converter to meet the needs of practical projects.4. In-depth study of the complex power conservation method, derived study methods about mutant structure waveguide-- the generalized scattering matrix. The TM11--HE11 mode converter has been simulated by three-dimensional electromagnetic simulation software CST, and optimization values for each parameter of the compact and efficient TM11--HE11 circular waveguide mode converter has been obtained.