Ultra-Wideband Flattened Design Enabling the Development of Sheet Beam Traveling Wave Tubes in the SHF Band

Considerable progress has been made in the development of sheet beam traveling-wave tubes (SB-TWTs) that operate in the millimeter-wave and terahertz domains. However, research pertaining to SB-TWTs operating in the super high frequency (SHF) band is notably lacking. In this article, the potential for the future advancement of SB-TWTs into the SHF band is investigated. To address the technical challenges of sideband oscillation and excessive size, an ultra-wideband flattened design has been proposed and verified. The proposed flattened design employs a flat electric field with 84.6% space occupation that has been shown to efficiently interact with the sheet beam while providing high phase consistency for electron modulation, thereby enhancing the concentration of the energy distribution of the sheet beam and improving overall efficiency. The adoption of sideband mode disturbance technology inherently eliminates upper sideband oscillation, releases the bandwidth limitation, and enables high power output. The analysis reveals that the 3-dB relative bandwidth reaches 41.2%, and the power bandwidth product exceeds 100 kW-GHz in ${X}$ -band. Moreover, the proposed design reduces the height of the vanes by 26.5% compared to traditional structures, which facilitates the possibility of compact periodic cusp magnet (PCM) focusing systems in the SHF band. Overall, these findings suggest that the proposed ultra-wideband flattened design offers a promising solution for the development of high-performance compact SB-TWTs that operate across a broad frequency range, including the SHF band.