A new topology to excite circular TE02 mode for studying of gyrotron traveling-wave tube (gyro-TWT) is presented. The mode generator consists of a rectangular TE10 to cross waveguide TE44 mode converter and a cross waveguide TE44 to circular TE02 mode converter. To obtain a high-purity TE02 mode output and make the generator compact, a cross waveguide with sidewall coupling apertures and a novel mode transition section with metal diaphragm are introduced. The proposed mode generator is fabricated and measured. A good agreement between simulation and measurement is obtained, and the 1-dB bandwidth from 28 to 34 GHz is obtained in back-to-back test. The angle-independent transmission demonstrates high mode purity and the presence of TE02 mode confirmed by the field pattern measurement. The mode exciter features high mode purity, broad bandwidth, and is easy to be fabricated, which can be applied to cold-test experiments of gyro-TWT components and the high power transmission line devices.

中文翻译：

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用于陀螺-TWT 研究的高纯度圆形 TE₀₂ 模式发生器

提出了一种新的拓扑结构来激发圆形 TE02 模式，用于研究回旋管行波管 (gyro-TWT)。模式发生器由矩形 TE10 到交叉波导 TE44 模式转换器和交叉波导 TE44 到圆形 TE02 模式转换器组成。为了获得高纯度的 TE02 模式输出并使发生器紧凑，引入了具有侧壁耦合孔径的交叉波导和具有金属隔膜的新型模式转换部分。所提出的模式发生器是制造和测量的。仿真和测量之间获得了良好的一致性，并且在背靠背测试中获得了 28 至 34 GHz 的 1 dB 带宽。与角度无关的传输证明了高模式纯度和场模式测量证实的 TE02 模式的存在。模式激励器具有模式纯度高、带宽宽、