Grating-Groove-Ladder Slow Wave Structure for W-Band Traveling Wave Tube

A new slow wave structure (SWS) named grating-groove-ladder (GGL) is proposed to extend the bandwidth of a conventional ladder (CL). Through the special arrangements of the grating-controlled EM modulation unit on the cover plate, the high-frequency characteristics of GGL-SWS have exhibited a wider bandwidth, good interaction impedance, and lower ohmic losses. Numerical calculations of beam-wave interactions confirm the good amplification performance of the GGL-TWT. The effectiveness of the GGL-TWT in extending the bandwidth is accompanied by a reduction in gain. The cold-test transmission characteristics of the GGL-SWS have demonstrated a good agreement with simulations in W -band. The fabricated GGL-SWS has also been proven to have good fabrication accuracy through morphology and surface roughness characterization. Therefore, GGL provides a viable solution for extending the bandwidth of CL.