A Broadband Suspended Coplanar Waveguide Slow wave Structure for Planar TWTs

In this paper, a wideband suspended coplanar waveguide (CPW) slow wave structure (SWS) for planar Traveling Wave Tubes (TWTs) is described with the analysis of its dispersion characteristics, interaction impedances and electric field distribution. Simulation results shows that the normalized phase velocity of the suspended CPW SWS changes only 0.007 for 26.5-40GHz, while the interaction impedances is higher than 12.7 Ohms. In addition, the existence of the metal ground plane can partly prevent the poorly-focused charges from hitting the dielectric substrate, which means the suspended CPW SWS is suitable for the design of broadband planar TWTs.