Design and Simualtion of a Ku-Band Input Coupling Structure TE□ 10→TE○ 11 for Gyro-TWT

摘要

In This paper,the design and simulation of a Kuband input coupling structure TE□10→TE○11 for the gyrotrontraveling-wave-tube (gyro-TWT) amplifier is presented in detail.The input mode TE10 from the rectangular R180 is converted into the circular polarized mode TE(○ 11) by the input coupling structure,which consists of the mode converter part and the mode polarized part. It isA quite complicated process to optimize the input coupling structure since the parameters such as the disk thickness of the windows,the space between the disk and the axis of the waveguide,the radius of the waveguide,the length of the mode polarizer and so on,are all adjustable reciprocally.Inorder to reduce the reflection loss and expand the bandwidth of the input port the matched method of the phase and the amplitude is adoptedInthe process of designing the input coupling structure. With the optimization of the parameters the bandwidth of the input coupling structure is equal to about 1.0 GHz and 2.0GHz respectively when the VSWR (voltage standingwave ratio) of the input port is equal to 1.2 and 1.4,which also corresponds to the 6.1% and 12.1% of the centre frequency respectively.