Illustration of A Novel 220GHz Symmetrical Double Slots Elliptical-Like Coupled-Cavity Slow Wave Structure

In this paper, a novel elliptical-like cavity symmetrical double slots coupled-cavity (EC-SDSCC) slow wave structure (SWS) is presented. The cross section of the cavity is two symmetrical semi-ellipses in two sides and a rectangle in the center. The dispersion characteristics of the novel SWS is studied. This novel SWS is suitable for G-band high-power sheet electron beam traveling wave tube (SB TWT) due to its
$\mathbf{1.25}\times \mathbf{0.3}\ \mathbf{mm}^{\mathbf{2}}$
large sheet electron beam tunnel and
$\sim \mathbf{11}\mathbf{\Omega}$
high coupling impedance. Compared with the corresponding cuboid cavity structure, the EC-SDSCC reduces about 30dB/m of metal losses which could increase the saturation output power and saturation gain significantly.