矩形波导TM11-TE10模式转换器的初步设计

设计了一种矩形波导隔断插板式TM11-TE10模式转换器。其结构是在矩形波导横截面窄边的中部,平行于横截面宽边插入一块金属平板,将其等分为上下两个矩形波导,将TM11模式转换为分别位于上下两个矩形波导内相位相反的TE10模式。然后分别在上下两个矩形波导内,平行于窄边等间距地插入一组金属薄板。TE10模式微波经过轴向长度差为合适值的上下两组插板后,相移差变为180,使原本相位相反的TE10模式转为同向,最后通过阻抗渐变合成单个波导的TE10模式。该模式转换器可与带状电子束高功率微波源共轴,其横向最大尺寸可与带状电子束高功率微波源矩形输出口保持一致,轴向长度较短,结构简单、紧凑。利用有限元算法仿真软件,对该设计方案进行了验证和初步优化设计。初步的设计结果表明：当相对带宽为10%时,TM11至TE10模式的转换效率大于-0.45 dB,可满足带状电子束高功率微波源对输出结构的设计要求。

Preliminary design of TM11-TE10 mode converter in rectangular waveguide

The design of a separate and plate-inserted mode converter for rectangular TM11-TE10 was presented. A metal flashboard, paralleling the wide edge, was inserted at the middle of the narrow edge, separating the rectangular waveguide into two equal parts, which transformed TE10 modes with reverse phases. A group of metal plates, paralleling the narrow edge, were inserted with the same space, both in two parts. While the difference of metal plates coaxial length between different parts was suitable, the TE10 modes of the two parts got 180 phase difference. Thereafter, the TE10modes from different parts were transformed with the same phase and compounded into one single TE10 mode by an impedance degression part. The mode converter could keep the same axis and transverse size of output port of high-power microwave source driven by sheet election beam. Its axial length was short and had simple and compact structure. The design was validated and preliminarily optimized by software with finite element algorithm. The transmission efficiency reached -0.45 dB, while bandwidth exceeded 10%, meeting the needs of high-power microwave source driven by sheet electron beams. All the results above offer a new technology for the design of high-power microwave generators with sheet electron beams and its radiation system.