Symmetric planar helix slow-wave structure with straight-edge connections for application in TWTs

A symmetric configuration for planar helix slow-wave structure (SWS) with straight-edge connections (PH-SEC) is proposed in this paper. This structure is compared with a previously proposed PH-SEC SWS on a thick substrate. The results at Ka-band are presented to show that the new structure has higher and more uniform coupling impedance and thus is more suitable for TWT applications.