3D printing of a metallic helix for traveling wave tube amplifiers operating in millimeter wave range

Traveling wave tube (TWT) amplifiers reach the highest output powers at mm-wave and THz frequencies. However, at these frequencies the slow-wave structures (SWS) reach a limit of manufacturing. In this paper, a 3D additive micromanufacturing technique (µAM) was used to fabricate a metallic helix. The helix has a pentagonal shape where the sides have a length of about 100 µm. The fabricated helix can be used as SWS in a TWT amplifier operating in a frequency range between 50 and 80 GHz. Simulations showed that the TWT can reach a gain higher than 30 dB at 77GHz and a 3 dB bandwidth of about 2 GHz.