Microfabricated Millimeter-Wave Traveling Wave Tubes

Millimeter and sub-millimeter wave vacuum electronic devices have been of great interest for a wide variety of applications, but fabrication of the sub-wavelength structures has been a persistent challenge. We present and compare fabrication approaches including CNC micromachining, 3D printed mold electroforming (3D PriME), and UV-photolithography for creating traveling wave tube circuits at 35, 95, 140 and 233 GHz, along with results. To date, CNC micromachining has yielded the best results up to 140 GHz.