In this paper, two types of coaxial coupler and waveguide coupler for different frequency helix traveling wave tubes (TWTs) are designed, fabricated and cold tested. The coaxial coupler includes of window ceramic and RF transformer section. At present multi-section impedance transformer design approach is used for wideband helix TWTs. In any helix TWT, impedance of the source is transformed to the characteristic impedance of helix. This is done by the quarter-wavelength (λ/4) impedance transformation approach. The simulated results of different types of couplers are carried out by HFSS and CST microwave studio software and compare with experimental results. Three-dimensional electromagnetic field simulators allowing the any geometry with port excitations it is possible to model the complex coaxial and waveguide type couplers with helix SWS assembly and predict its desired return loss performances.

中文翻译：

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螺旋TWT的同轴和波导耦合器设计

本文针对不同频率的螺旋行波管（TWT）设计，制造和冷测试两种同轴耦合器和波导耦合器。同轴耦合器包括窗口陶瓷和RF变压器部分。目前，多段阻抗变压器设计方法被用于宽带螺旋TWT。在任何螺旋TWT中，源阻抗都转换为螺旋的特征阻抗。这是通过四分之一波长（λ/ 4）阻抗变换方法完成的。利用HFSS和CST微波演播室软件对不同类型耦合器的仿真结果进行了仿真，并与实验结果进行了比较。