This article proposes a longitudinal output structure in Ka-band sheet beam traveling-wave tube (SBTWT) with an ultrawideband transmission and high breakdown collector voltage. A novel electromagnetic bandgap (EBG) cutoff structure is designed to separate the slow-wave structure (SWS) and the depressed collector. The large stopband property of the EBG structure is applied to achieve not only the high transmission and the low gap leakage but also the long gap distance to provide a high breakdown voltage of the depressed collector. The 3-D simulations of a single longitudinal structure show a full Ka-band (26.5–40 GHz) reflection of less than −20 dB and gap leakage less than −0.02 dB. The entire longitudinal output collector, including two large gaps cutoff structures and the over mode electron collecting parts, is designed and manufactured. The simulations show a bandwidth of 10.4 GHz with a reflection coefficient ${S} _{\mathbf {11}}$ of lower than −20 dB. The cold test demonstrates the wild bandwidth of ~11.1 GHz with a reflection coefficient ${S} _{\mathbf {11}}$ of lower than −15 dB. The hot test reveals a stable collector dc voltage of −14.2 kV.

中文翻译：

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Ka波段薄板束行波管的宽带高压纵向输出结构

本文提出了一种具有超宽带传输和高击穿集电极电压的Ka波段片束行波管（SBTWT）的纵向输出结构。设计了一种新颖的电磁带隙（EBG）截止结构，以将慢波结构（SWS）和凹陷的集电极分开。EBG结构的大阻带特性不仅可实现高透射率和低间隙泄漏，而且可实现长间隙距离，从而提供凹陷的集电极的高击穿电压。单个纵向结构的3D模拟显示，完整的Ka波段（26.5–40 GHz）反射小于-20 dB，间隙泄漏小于-0.02 dB。设计并制造了包括两个大的间隙截止结构和过模式电子收集部件在内的整个纵向输出收集器。 $ {S} _ {\ mathbf {11}} $ 低于-20 dB。冷测试表明，反射系数约为11.1 GHz的通配带宽 $ {S} _ {\ mathbf {11}} $ 低于-15 dB。热测试显示集电极的稳定直流电压为-14.2 kV。