The HE₁₁ hybrid mode, propagating in an overmoded corrugated circular waveguide, is widely used for low loss transmission of high-power microwaves. Due to the inherent broadband frequency behaviour, this will be also essential for future broadband high-power radar applications, like space debris observation in low earth orbit (LEO). A promising amplifier concept for such radar sensors is a helical gyro-TWT. However, since the HE₁₁ hybrid mode is not suitable for electron-beam-wave interaction in this kind of vacuum electron device, an additional mode converter is required. The present paper addresses the design procedure of a broadband high-power mode converter, designed for a helical gyro-TWT intended for future broadband high-power radar applications in the W-band. The interaction mode of the helical gyro-TWT under consideration can be easily transferred to the circular waveguide TE₁₁ mode. Therefore, a TE₁₁ ↦ HE₁₁ mode converter is addressed here. The design procedure is based on a scattering matrix formalism and leads to a high HE₁₁ mode content of ≥98.6% within the considered frequency range from 92 GHz to 100 GHz. Inside this frequency band, the mode content is even better and reaches ≈ 99.7% at ≈95 GHz. This allows broadband frequency operation of a helical gyro-TWT and is suitable for broadband high-power radar applications.

HE ₁₁混合模式在过调制的波纹圆形波导中传播，被广泛用于高功率微波的低损耗传输。由于固有的宽带频率特性，这对于未来的宽带大功率雷达应用（如低地球轨道（LEO）中的空间碎片观测）也必不可少。这种雷达传感器的一个很有前途的放大器概念是螺旋陀螺仪TWT。但是，自从₁₁混合模式不适用于这种真空电子设备中的电子束-波相互作用，因此需要附加的模式转换器。本文讨论了宽带大功率模式转换器的设计程序，该转换器是为螺旋陀螺TWT设计的，旨在用于W波段的未来宽带大功率雷达应用。所考虑的螺旋陀螺-TWT的相互作用模式可以容易地转换为圆形波导TE ₁₁模式。因此，此处介绍了TE ₁₁  →HE ₁₁模式转换器。设计过程基于散射矩阵形式，导致HE ₁₁高在从92 GHz到100 GHz的频率范围内，≥98.6％的最大模式含量。在此频段内，模式内容甚至更好，在≈95GHz时达到≈99.7％。这允许螺旋陀螺仪TWT的宽带频率操作，并且适合于宽带大功率雷达应用。