Abstract

We demonstrate how the use of glide symmetry (GS) can be exploited as a beam-wave interaction mechanism to establish very wideband operation of a traveling-wave tube (TWT) amplifier. We apply the concepts to a glide-symmetric double corrugated gap waveguide (GSDC-GW) slow wave structure (SWS), though the discussed principles are general. The advantages of GS are twofold: 1) it closes the bandgap at the 3 pi-point when structural alignment is maintained, enabling wideband operation and 2) the backward wave is not z-polarized at the spatial harmonic of interest, mitigating the risk of backward-wave oscillations. Furthermore, an SWS based on an electromagnetic bandgap (EBG) waveguide eliminates the need for a conductive connection between the top and bottom waveguide plates, simplifying the assembly process. The TWT performance is evaluated via particle-in-cell (PIC) simulations that reveal a 3-dB bandwidth of approximately 12GHz spanning from 54.5 to 66.3GHz, accompanied by a maximum gain of 23dB. This work places the GSDC-GW structure among promising SWSs topologies for TWTs operating at millimeter-wave frequencies with comparable bandwidth and gain, and provides a physics-based path for the beam-wave interaction mechanism enabled by GS for future wideband, higher power vacuum electron devices.