The folded groove guide, an original slow-wave structure for millimeter-wave TWT

The folded rectangular groove guide, an original slow-wave structure (SWS) , which is evolved from a conventional rectangular groove guide by bending the groove along its longitudinal direction, can operate with the sheet electron beam or the circular electron beam. The groove shape can be various,such as triangle, circle, trapezoid, etc. The electromagnetic characteristics, and the beam-wave interaction of a traveling wave tube based on this structure at 3mm wavelength are presented. Furthermore, the influences of different groove shape on the high-frequency characteristics are also discussed. From our calculations, the folded rectangular groove guide possesses larger interaction impedance and lower ohmic loss than those of a folded rectangular waveguide with the same size. Calculation results reveal the potential of the folded groove guide, which is easy to fabricate, for wideband, low-loss, and high-power millimeter-wave submillimeter-wave TWT applications.